5 Logical Puzzles That Will Bend Your Brain

5 Logical Puzzles That Will Bend Your Brain (Answers Included!)

A Post By: Anthony Persico

Are you looking to take on some fun and challenging logical puzzles and put your brain power to the test?

Attempting to solve logic puzzles is one of the best ways to improve your problem-solving and logical thinking skills while having lots of fun at the same time.

Today’s post shares a collection of 5 logical puzzles for kids and adults that gradually progress in difficulty—and there’s also a special bonus puzzle that has been stumping people for over 100 years!

Note that the solution to each logic puzzle is included at the bottom of the post (we recommend trying all of the problems on your own first and then checking to see if your answers are correct afterwards).

Are you ready to get started?

Image: Mashup Math FP

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5 Logical Puzzles That Will Bend Your Brain

Some of these puzzles can be solved in under one minute, while others are tricky enough to stump you all day long, putting your brain to the test!

Today, you’ll have a chance to give your brain a workout by figuring out a few of these famous logic and number puzzles.

So, are you up for the challenge? And don’t forget to try the bonus puzzle—a simple yet tricky riddle that has been around for over 100 years.

And if you need more detailed explanations of how to solve each logic puzzle, check out our 5 Logical Puzzles That Will Bend Your Brain video below, and be sure to click the like button and leave a comment!

Watch the 5 Logic Puzzles Video:

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Logical Puzzle #1

How many total blocks are in the diagram below?

Keep reading to the bottom of this page to see the answer key AND click here to see the video that explains the solution to this problem.

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Logical Puzzle #2

How far can a bear walk into the woods?

Image: Mashup Math FP

Keep reading to the bottom of this page to see the answer key AND click here to see the video that explains the solution to this problem.

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Logical Puzzle #3

How can you flip the gummy bear pyramid upside down by moving only 3 gummy bears?

Keep reading to the bottom of this page to see the answer key AND click here to see the video that explains the solution to this problem.

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Are you looking for more super fun Math Riddles, Puzzles, and Brain Teasers to share with your kids?

The best-selling workbook 101 Math Riddles, Puzzles, and Brain Teasers for Kids Ages 10+! is now available as a PDF download. You can get yours today by clicking here.

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Logical Puzzle #4

On Bert’s 14th Birthday, his younger brother Chip was half his age. If today is Bert’s 31st birthday, how old is Chip?

Keep reading to the bottom of this page to see the answer key AND click here to see the video that explains the solution to this problem.

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Logical Puzzle #5

If there are 7 bears in a room and they each hug each other once and only once, how many total bear hugs were there altogether?

Keep reading to the bottom of this page to see the answer key AND click here to see the video that explains the solution to this problem.

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Bonus Logical Puzzle!

An explorer who walks one mile south, one mile east, and one mile north and ends up right back where he started. While he is walking, he sees a bear. What color is the bear?

Keep reading to the bottom of this page to see the answer key AND click here to see the video that explains the solution to this problem.

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Ready for the answers?

Remember that there’s no rush to find the answers to today’s logic puzzles. It’s ok to wait to until you’ve found an answer to each problem before scrolling down to see the answers below.

ANSWER KEY:

1.) 11 Blocks

2.) Half-Way (after that, the bear is walking out of the woods)

3.) Diagram:

4.) Chip is 24 years old

5.) 21 Hugs

Bonus: The Bear is White (Polar Bear at the North Pole)

Image: Mashup Math FP

Are you looking for more super fun Math Puzzles to share with your kids?

My best-selling workbook 101 Daily Math Challenges for Engaging Students in Grades 3-8 is now available as a PDF download. You can get yours today by clicking here.

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Did I miss your favorite math riddle for kids? Share your thoughts, questions, and suggestions in the comments section below!

(Never miss a Mashup Math blog--click here to get our weekly newsletter!)

By Anthony Persico

Anthony is the content crafter and head educator for YouTube's MashUp Math and an advisor to Amazon Education's 'With Math I Can' Campaign. You can often find me happily developing animated math lessons to share on my YouTube channel . Or spending way too much time at the gym or playing on my phone.

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10 Free Kindergarten Math Worksheets (PDF Downloads)

10 Free Kindergarten Math Worksheet PDFs

A Post By: Anthony Persico

Are you looking for a handy of collection of 10 fun and engaging worksheets for kindergarten-level students? All of the following free kindergarten math worksheets come as PDF files that are easy to download, print, and share for use at home or in the classroom. Enjoy!

How to Use These Worksheets:

This collection of free kindergarten math worksheets can be shared with children ages 4 and up. The worksheets cover introductory math topics including identifying and writing numbers from 0 to 13, counting, and grouping. The activities are sequential and are designed to gradually include larger numbers and groupings (starting with single-digits and eventually moving towards double-digits including the low teens). It is recommended that children complete the activities in order from worksheet one to worksheet ten in order to experience and grasp the progression from smaller numbers to larger ones.

These worksheets can be used by kindergarten teachers in the classroom and/or by parents with their kids at home and in homeschooling settings. Based on your child’s ability levels and past exposure to numbers and counting, you can choose to either allow them to work on the worksheets independently or to work with them while they complete the activities.

How to Download and Print:

Below you will find preview images and links to download all ten kindergarten math worksheets. There will also be a link denoted by a download symbol ⤓. Once you click on one of these links, the corresponding worksheet will download in a new window as a PDF file. Once the file is downloaded, you can save it to your personal device and or print the worksheet.

If you need a more detailed explanation of how to save and/or print any of these free pdf worksheets, please view our video tutorial by clicking this link.

*Note that you can click on any of the worksheet images to see an enlarged preview before you download.

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10 Free Kindergarten Math Worksheets PDFs

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1.) Practice with Single Digit Numbers

This worksheet lets children practice writing the numbers zero through seven and includes tracing lines. This foundational skill is a key prerequisite to learning how to count and eventually add values together.

⤓ Click Here to Download PDF Worksheet #1

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2.) Focus on 4

This worksheet focuses on writing the number four and identifying the symbol in comparison with other single-digit numbers (up to 6). Children must be able to identify and write all of the single-digit numbers, including zero, before moving onto double-digits.

⤓ Click Here to Download PDF Worksheet #2

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3.) Sixes and Sevens!

This worksheet focuses on writing the numbers six and seven and identifying whether there are six or seven objects in a given set. This worksheet provides important practice with comparing and contrasting single-digit numbers.

⤓ Click Here to Download PDF Worksheet #3

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4.) Practice with 8, 9, and 10

This worksheet focuses specifically on writing, identifying, and counting the values 8, 9, and 10. It also introduces the first double-digit number, ten, as a naturally coming after 8 and 9.

⤓ Click Here to Download PDF Worksheet #4

(Remember that it’s perfectly fine for children to rely on finger counting to help them with any of these worksheets)

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5.) Practice Counting Objects

This worksheet focuses on counting and identifying numbers from zero to ten. In this activity, students have to identify and circle the correct value for each object shown in the diagram.

⤓ Click Here to Download PDF Worksheet #5

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6.) Practice Counting and Writing Numbers

This worksheet gives children more practice with identifying and counting the numbers from one to ten and gives them extra practice with writing these numbers by hand.

⤓ Click Here to Download PDF Worksheet #6

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7.) Practice Counting Objects

This worksheet focuses on counting and identifying numbers from one to ten. In this activity, students have to identify and circle the correct value for each object shown in the diagram.

⤓ Click Here to Download PDF Worksheet #7

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8.) Practice Comparing Numbers

This worksheet focuses on identifying and comparing values between three and ten. This foundational skill is a key prerequisite to understanding composite numbers and being able to add, subtract, multiply, and divide.

⤓ Click Here to Download PDF Worksheet #8

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9.) Writing Numbers 10 through 13

This worksheet focuses on the double-digit numbers from ten to thirteen and gives children a guided practice opportunity to identify and write these numbers by hand.

⤓ Click Here to Download PDF Worksheet #9

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10.) Focus on 11

This worksheet focuses on identifying the number eleven when grouped with other double-digit numbers (10, 12, and 13). This activity helps children to become more comfortable working with and identifying double-digit numbers and prepares them to eventually learn the numbers 14 through 20.

⤓ Click Here to Download PDF Worksheet #10

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WAIT!

Do YOU Want On-Demand Access to All of Our Kindergarten Math Lesson Resources, Worksheets, and Activities?

Do you want on-demand access to ALL of our kindergarten math activities, worksheets, lesson plans, and puzzle libraries?

Mashup Math Members gain access to thousands of engaging grade-specific math puzzles, activities, and worksheets for grades K-8. Learn more and sign up for a free 7-day trial today!

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(Never miss a Mashup Math blog--click here to get our weekly newsletter!)

By Anthony Persico

Anthony is the content crafter and head educator for YouTube's MashUp Math and an advisor to Amazon Education's 'With Math I Can' Campaign. You can often find me happily developing animated math lessons to share on my YouTube channel . Or spending way too much time at the gym or playing on my phone.

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10 Free Maths Puzzles with Answers!

10 Fun (and Free) Maths Puzzles with Answers

A Post By: Anthony Persico

Are You Ready for These Super Fun (and Slightly Brain-Bending) Maths Puzzles?

Every month, thousands of individuals, young and old, search the internet for maths puzzles with answers. Why? Because working on challenging and engaging maths puzzles is more than just a recreational activity. In fact, studies show that working on maths puzzles has several educational benefits including boosting interest in mathematics, improving problem-solving skills and algebra skills, and cultivating reflective learning abilities.

So, if you’re one of these individuals looking to reap the benefits of working on challenging maths puzzles (while having some serious fun while doing so), then you’re in the right place!

Now that you know the benefits of challenging your mind by trying to solve maths puzzles, you’re just about ready to try and solve today’s collection of super fun maths riddles.

Note that these maths riddles with answers are appropriate for individuals ages 12 and up.

Before you get started, here are a few tips to keep in mind when attempting to solve any of today’s maths puzzles:

• Read every maths puzzle carefully and allow yourself to think for a bit before getting started.

• Use proven strategies like visualizing, diagram drawing, and trial-and-error.

• You’re going to struggle! When you find yourself feeling discourages and/or messing up, that means you are in the process of reaping the benefits of solving maths puzzles and improving your problem-solving skills!

• Whenever you find an answer, ask the question “does this solution make sense?”

• If at any time you get stuck, close the page and take a break. This is a good time to take your mind off of the problem by doing something else like going out for a walk. The puzzle will likely become more manageable when you revisit it later on.

Practice Problem: How Many Squares?

Before you attempt the 10 Maths Puzzles with Answers on your own, you may want to get warmed-up with a relatively easy maths puzzle just to get your brain fired up and ready for some more challenging problems later on.

Of course, you can choose to continue on and skip this practice problem if you’d like.

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Here is the problem:

How many SQUARES are in the 3x3 grid?

How to solve:

This is a relatively straightforward maths puzzle to solve, provided that you consider two pieces of information:

• A square is a plane figure with four equal sides and four right angles.

• Some squares are overlapping in the diagram.

Want to try the problem on your own? If so, don’t go any further. Stop here and try to solve the puzzle and come on back when you’re finished.

…

The most common way to solve this problem is to consider all the squares, from smallest to largest, and count them as follows:

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Final Answer: 14 Total Squares

Wasn’t that fun? Now you are ready to move onto some more challenging maths puzzles!

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10 Fun Maths Puzzles with Answers

Each of the following math puzzles with answers includes an image graphic. Click on any image to enlarge. The complete answer key for all 10 maths puzzles is included at the bottom of the page.

Have fun!

1.) Maths Puzzles 01 of 10: How Many Rectangles?

This problem may seem very similar to the practice problem, but the subtle difference between Squares and Rectangles is a very big deal that makes this problem rather tricky. (Click here to learn more about this controversial maths puzzle)

Can you solve it?

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(Hint: By definition, is a square a rectangle?)

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2.) Maths Puzzle 02 of 10: Factors and Fruit

Problem: If each piece of fruit in the diagram below is equal to one of the following numbers: 1, 2, 3, or 5, then what is the value of each fruit so that both equations are true?

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3.) Maths Puzzle 03 of 10: Moon Math

Problem: What is the value of the missing number “?” in the lunar diagram below?

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Hint: Look for a pattern.

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4.) Maths Puzzle 04 of 10: Which is More Pizza?

Problem: Which deal gets you the most pizza (if each deal costs the same amount):

• One 18” pizza pie, or

• Two 12” pizza pies

Can you solve it?

Use the area of a circle formula: A= π(r^2)

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5.) Maths Puzzle 05 of 10: Super Maths!

Problem: Find the value of each symbol and the ‘?’ in the puzzles below:

Puzzle 1

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Puzzle 2

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Puzzle 3

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Are you looking for more super fun Maths Riddles, Puzzles, and Brain Teasers?

The best-selling workbook 101 Math Riddles, Puzzles, and Brain Teasers for Ages 10+! is now available as a PDF download. You can get yours today by clicking here.

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6.) Maths Puzzle 06 of 10: How Many Triangles

Problem: What is the total number of triangles in the diagram below?

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7.) Maths Puzzle 07 of 10: Matchsticks Maths

Problem: Make the maths equation true by moving ONE AND ONLY ONE matchstick?

(*Bonus if you can find all three possible answers)

See Also: video tutorial on solving the matchstick maths problem.

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8.) Maths Puzzle 08 of 10: How Many Total Handshakes?

Problem: If there are 20 people in a room and they shake every other person’s hand once and only once, how many handshakes would take place?

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9.) Maths Puzzle 09 of 10: Shopping Spree!

Problem: At the mall, the total cost of a pair of shoes and a hoodie is $150. The cost of the hoodie is $100 more than the cost of the pair of shoes. How much does each item cost?

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10.) Maths Puzzle 10 of 10: Parking Lot Puzzle

Problem: In the diagram below, what is the number of the parking spot occupied by the car?

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11.) Bonus Maths Puzzle! : The Big Triple!

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MATHS PUZZLES ANSWER KEY:

1. 36 Total Rectangles (click here to learn more about how to solve this problem)

2. Melon=5, Apple=2, Grapes=3, Lemon=1

3. ?=8 (the relationship between the diagonals are cubes and cube roots)

4. Area of 18” Pizza: ~254.3 square inches > Area of two 12” pizzas: 226 square inches

   (click here to learn more about how to solve this problem)

5. Puzzle #1: DK=12, Bananas=8, Barrell=4, ?=24

   Puzzle #2: Mario=12, Peach=12, Toad=6, Bowser=0, ?=30

   Puzzle #3: Van=8, Zombie=9, Scooby=5, ?=77

6. 27 Total Triangles

7. 8-4=4, 5+4=9, 0+4=4 (Here is a great video explanation)

8. 190 handshakes (19+18+17+16+...+3+2+1=190)

9. Hoodie costs $125, Shoes cost $25

10. 87 (click here to learn how to solve this problem)

11. (BONUS!) 1+2+3=6 and 1 x 2 x 3 = 6

Click here to sign up for our math education mailing list to start getting free K-12 math activities, puzzles, and lesson plans in your inbox every week!

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Do YOU Want More Fun Math Riddles, Puzzles, and Brain Teasers?

Check out our math riddle videos on YouTube!

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Did I miss your favorite math riddle for adults? Share your thoughts, questions, and suggestions in the comments section below!

(Never miss a Mashup Math blog--click here to get our weekly newsletter!)

By Anthony Persico

Anthony is the content crafter and head educator for YouTube's MashUp Math and an advisor to Amazon Education's 'With Math I Can' Campaign. You can often find me happily developing animated math lessons to share on my YouTube channel . Or spending way too much time at the gym or playing on my phone.

You Might Also Like…

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Do Not Celebrate Opposite Day with These Boring Math Puzzles

Opposite Day is January 25th! Are YOU Ready to Celebrate in Your Math Classroom?

This silly holiday is a favorite among elementary and middle school. If you want to channel some of their opposite day enthusiasm into fun math learning experiences, then definitely do not share today’s fun opposite day-themed math puzzles for grades K-8 in your upcoming lesson plans!

Today is Opposite Day!

Actually, check that, today is not opposite day.

Or is it not not opposite day?

Confusing? Yes. But either way, Opposite Day, celebrated on January 25th each year, is a day when kids across the country rejoice as they get to indulge in fun and silliness, claim broccoli as their favorite food, and math as their least favorite subject ;)

Since my students love to make silly statements only to claim that the given day was indeed opposite day, I wanted to do something extra fun and special for them. So, I created some super fun (I mean extremely boring) Opposite Day Math Puzzles for Grades K-8, plus a very special Bonus Opposite Day Math Puzzle for Grades 4-8 that has two solutions (one when solved right-side-up and another when solved upside-down!).

These kinds of activities are perfect for mixing up your instructions, giving your students opportunities to think creatively about math, and adding some fun learning experiences into your lesson plans.

All of the math puzzles and activities share below are opposite day-versions from the puzzles featured in our best-selling workbook 101 Daily Math Puzzles for Challenging Students in Grades 1-8 (Volume 2)

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HOW TO DOWNLOAD: You can download any of the puzzles below by right-clicking and saving the file to your computer and/or dragging-and-dropping the file to your desktop.

ANSWER KEY: Scroll to the bottom of this post to access the complete answer key.

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1.) Opposite Day Puzzle #1: Grades K-2

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(keep reading to access the answer key at the end of this post)

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2.) Opposite Day Puzzle #2: Grades 3-5

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(keep reading to access the answer key at the end of this post)

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3.) Opposite Day Puzzle #3: Grades 6-8+

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(keep reading to access the answer key at the end of this post)

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3.) Opposite Day Bonus! (for Grades 4-8+)

This special opposite day puzzle has two solutions! Solve it once right-side up, then flip it and solve it again upside-down. Can you find both answers?

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(keep reading to access the answer key at the bottom of this post)

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All of today’s math puzzles are opposite day versions of the puzzles shared in our best-selling workbook: 101 Daily Math Challenges for Grades 1-8 Volume 2

Here are some samples from the book:

Grades 1-3 Puzzle

Grades 4-5 Puzzle

Grades 6-8 Puzzle

Multiplication Table Puzzle

Helpful Hints Sample

101 Daily Math Challenges for Grades 1-8 Volume 2 is now available as a PDF download. You can get yours today by clicking here.

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ANSWER KEY:

• Puzzle #1 (Grades K-2): Day & Night=5 Balloons=7 Toilet=4, ?=1

• Puzzle #2 (Grades 3-5): Day & Night=12 Up & Down=18 Balloons=2 Toilet=12, ?=44

• Puzzle #3 (Grades 6-8+): Day & Night=91 Up & Down=37 Balloons=9 Toilet=91 , ?=46

• Bonus Puzzle:

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Did I miss your favorite math holiday riddle for kids? Share your thoughts, questions, and suggestions in the comments section below!

(Never miss a Mashup Math blog--click here to get our weekly newsletter!)

By Anthony Persico

Anthony is the content crafter and head educator for YouTube's MashUp Math and an advisor to Amazon Education's 'With Math I Can' Campaign. You can often find me happily developing animated math lessons to share on my YouTube channel . Or spending way too much time at the gym or playing on my phone.

You Might Also Like…

10 Fun Math Riddles for Adults (with Answers)

10 Fun (and Free) Math Riddles for Adults

A Post By: Anthony Persico

Who says that having fun solving math problems and puzzles is only for children? 

There are over one hundred thousand web searches for math riddles for adults every month, according to Google. If you are one of these individuals searching for fun, engaging, and sometimes brain-bending math riddles and brain teasers made specifically for adults, then grab a pen and paper and get ready for a challenge!

Image: Mashup Math FP

Working on math riddles as an adult is a great way to keep your mathematical reasoning and problem-solving skills sharp while having a lot of fun at the same time. Today’s post shares 10 super fun math riddles for ages 18+ that were created to challenge the adult mind and they are appropriate for individuals ages 16 and up.

Each math riddle is a unique opportunity to apply your problem-solving skills, mathematical thinking, arithmetic, reasoning, and logic. It is recommended that have a pen, paper, and a calculator on-hand when attempting to solve any of these riddles, as drawing a diagram and working out the math by hand can be extremely helpful.

Helpful Advice Before You Begin…

Before you start working on solving all 10 riddles, here are a few helpful hints for overcoming the inevitable moments when you get stuck and/or are considering giving up on trying to solve the problem:

•  Read each math riddle carefully and think about the problem for a while before doing anything.

• Utilize strategies such as visualizing, drawing diagrams, and trial-and-error when you don’t know where to start.

• Don’t get discouraged! When you are struggling and making mistakes, you are in the process of learning. This is called having a growth mindset!

• Whenever you find a solution, ask yourself “does my answer make sense?”

• If you are stuck on a problem, take a short break, and do something else like taking a short walk. You’ll be surprised by how the problem will become more manageable when you return.

Practice Problem: Captain Anne’s Coins

In case you are feeling a bit rusty and need a quick refresher on how to go about solving math riddles, below is a bonus practice problem that is worked out step-by-step. You can choose to skip this practice problem if you would like.

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Image: Mashup Math MJ

Here is the problem:

Captain Anne has a chest full of coins.

When she arranges the coins in groups of two, there is one single coin left over. When she arranges the coins in groups of three, five, or six, there is also just one single coin left over. But when she arranges the coins in groups of seven, there are no coins left over.

What is the fewest amount of coins she could have?

 How to solve:

This is a very challenging problem to solve mentally, so using a pen and paper will be a big help (if you are a hands-on learner, you can use real coins to support your thinking and model how to solve this riddle).

In this case, let’s go ahead and create a chart that models all of the possible scenarios, starting with the fact that when she arranges the coins in groups of two, there is one single coin left over. Let’s assume that this is the only true statement that we know, then we could conclude that her total number of coins must be one more than a number that is divisible by two. The possibilities would include:

Possible Coin Totals for Groups of 2: 3, 5, 7, 9, 11, 13, 15, 17, …

You can then go ahead and repeat this process for the statement when she arranges the coins in groups of three, five, or six, there is also just one single coin left over.

Possible Coin Totals for Groups of 3: 4, 7, 10, 13, 16, 19,…

Possible Coin Totals for Groups of 5: 6, 11, 16, 21, 26, 31,…

Possible Coin Totals for Groups of 6: 7, 13, 19, 25, 31, 37,…

Finally, make a list of possibilities for the last statement: but when she arranges the coins in groups of seven, there are no coins left over.

Possible Coin Totals for Groups of 7: 7, 14, 21, 28, 35, 42,…

Now that you have a list of coin total possibilities for each statement, you have to the identify the lowest number that is present on every list. A coin total of 7 is a solid contender because it shows up on almost every list…except for the groups of 5, so the answer must be a different number.

At this point, you’ll notice that there isn’t a number that appears on every list, so you’ll have to start extending them as follows until you find the answer:

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Notice that the smallest number that appears on every list is 91.

Final Answer: The fewest number of coins that Captain Anne could have is 91.

Now that you have an idea of how to solve these kinds of math brain teasers, you can try to solve them all! There is a complete answer key at the bottom of this post!

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10 Fun Math Riddles for Adults

Each of the following math riddles includes an image graphic. Click on any image graphic to enlarge. A complete answer key is included at the bottom of the post.

1.) Math Riddle One of Ten: How Many Handshakes?

If there are 20 people in a room and they each shake each other’s hand once and only once, how many handshakes were there all together?

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Image: Mashup Math MJ

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2.) Math Riddle Two of Ten: The Fruit Factor

Each of the fruits in the diagrams below are equal to one of the following whole numbers: 1, 2, 3, or 5. Find the value of each fruit so that both of the equations would be true.

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Image: Mashup Math

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3.) Math Riddle Three of Ten: Water Jug Dilemma

You are given an 8-gallon jug filled with water, and also two empty jugs: one that holds 5 gallons and another that holds 3 gallons. Using these three jugs, how can you measure exactly 4 gallons of water?

(This riddle was famously presented to (and successfully solved by) Bruce Willis and Samuel L. Jackson’s characters in Die Hard with a Vengeance.)

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Image: Mashup Math MJ

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4.) Math Riddle Four of Ten: The Combo Platter

Oliver orders the combo platter for lunch every Wednesday.

One day, he noticed that the amount he paid for his sushi platter was a rearrangement of the digits of the amount of money he had in his pocket.

He also noticed that the money he had left-over after paying was also a rearrangement of the same three digits.

How much money did Oliver start with?

Image: Mashup Math MJ

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5.) Math Riddle Five of Ten: Amazing Eights

If you had to write down all of the whole numbers between 1 and 100, how many times would you have to write the number 8?

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Image: Mashup Math Flaticon

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Are you looking for more super fun Math Riddles, Puzzles, and Brain Teasers?

The best-selling workbook 101 Math Riddles, Puzzles, and Brain Teasers for Ages 10+! is now available as a PDF download. You can get yours today by clicking here.

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6.) Math Riddle Six of Ten: Missing Cards

A few playing cards are missing from a standard 52-card deck. Three cards remain when you deal the entire deck to four people. And two cards remain when you deal the entire deck to three people OR if you deal the entire deck to five people. How many cards are missing from the deck?

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Image: Mashup Math FP

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7.) Math Riddle Seven of Ten: Movin’ Matchsticks

How can you make the equation below true by moving only ONE matchstick?

(*Bonus points if you can find three possible solutions!)

Check out this video tutorial on how to solve the famous matchstick problem.

Image: Mashup Math

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8.) Math Riddle Eight of Ten: Extra Eggs

Jenny has ten chickens that lay eggs every day. She wants to give away her extra eggs to her neighbors, but she wants to give each neighbor an equal number of eggs. She figures out that she needs to give 7 of her neighbors eggs for them to get the same amount, otherwise there is one egg left over.

What is the smallest number of eggs she needs for this situation to be true?

Image: Mashup Math MJ

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9.) Math Riddle Nine of Ten: The Fruit Man

Mr. Baccigalupi sells and delivers crates of fruit from his grocery store to the people in his neighborhood. He can either put 8 large pieces of fruit or 10 small pieces of fruit into a crate. In one shipment, he sent a total of 96 pieces of fruit. If the number of large pieces of fruit is greater than the number of small pieces of fruit, how many crates of fruit did he deliver?

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Image: Mashup Mat MJ

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10.) Math Riddle Ten of Ten: The Juiced Baseball

You have 7 baseballs that all weigh the same except for one, which is lighter than the others. Using a balance scale, how can you figure out which baseball is the lighter one if you only get two chances to weigh them?

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Image: Mashup Math MJ

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11.) Bonus Math Riddle! : My Three Daughters

A saleswoman knocks on an apartment door and a man answers. They have the following conversation:

Saleswoman: Hello sir, how many children do you have and what are their ages?

Image: Mashup Math MJ

Man: I have three daughters and I will give you a hint to help you figure out how old they are: if you multiply my 3 daughters’ ages, you will get 36.

Saleswoman: That is not enough information!

Man: Well, if you add up my daughters’ ages, the sum is the number of my next-door neighbor’s apartment.

Saleswoman (after looking at the number on the front door of the next apartment): That is still not enough information!

Man: The last hint that I will give you is that my oldest daughter has green eyes.

What are the ages of the man’s three daughters?

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ANSWER KEY:

1. 190 handshakes (19+18+17+16+...+3+2+1=190)

2. Melon=5, Apple=2, Grapes=3, Lemon=1

3. Start by completely filling up the 5-gallon jug with water. Next,

   pour water from the 5-gallon jug into the 3-gallon jug until it is completely full (leaving 2 gallons in the 5-gallon jug). Then, pour all of the water from the 3-gallon jug back into the 8-gallon jug. Next,

   pour the two gallons of water in the 5-gallon jug into the 3-gallon jug,

   which would leave it with exactly one gallon of available space. Then,

   completely fill the 5-gallon jug a second time. Finally, pour water

   from the 5-gallon jug into the 3-gallon jug until it is completely full

   (thus filling up the one gallon of available space in the 3-gallon jug),

   which leaves you with exactly four gallons of water in the 5-gallon

   jug! (Here is a video explanation that you may find helpful.)

4. Oliver started with $9.54. The value of the money can be written using three digits, so it has to be between $1.01 and $9.99. There is only one set of numbers that works:$4.59 + $4.59 = $9.54

5. 20 Times

6. 5 cards are missing

7. 8-4=4, 5+4=9, 0+4=4 (Here is a great video explanation)

8. The number of eggs must be one more than a number that is divisible by 2, 3, 4, 5, and 6 since each of these numbers leaves a remainder of 1. Therefore, the total is 301 eggs.

9. 11 Crates Total:
   7 filled with large fruit (7 x 8 = 56 pieces of fruit)
   4 filled with small fruit (4 x 10 = 40 pieces of fruit) So there are 11 total crates and 96 pieces of fruit.

10. Start by putting three baseballs on each side. If the scales are even, then the baseball ball that was excluded is the lighter one. But if they aren’t even, one side will weigh down while the other side rises up (this is the lighter side). In this case, one of the three baseballs on the lighter side is the light baseball. You can then take these three baseballs and put one on each side of the scale. If the sides are even, then the excluded baseball is the lighter one. And if they aren’t even, then the one that is lighter is the baseball that you are looking for.

11. (BONUS!) 2, 2, and 9 - Start by finding all of the groups of three numbers that multiply to 36 and write down their sums:

Since 13 is the only sum that repeats and because the salesman says that knowing the apartment number is not enough information, you can narrow it down to two trios: (6 6 1) and (2 2 9). And since the man says that his oldest daughter has green eyes, you know that he only one oldest daughter, so you can rule out (6 6 1).

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By Anthony Persico

Anthony is the content crafter and head educator for YouTube's MashUp Math and an advisor to Amazon Education's 'With Math I Can' Campaign. You can often find me happily developing animated math lessons to share on my YouTube channel . Or spending way too much time at the gym or playing on my phone.

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