84 Fun Math Riddles (For Adults & Kids)

Riddles are fun, but they can also be educational. All riddles provide opportunities for creative thinking and problem solving. However, math riddles take that to the next level.

Our math riddles are perfect not only for family fun, but also prove valuable in educational venues, such as classrooms and camps. Our article begins with some relatively easy math riddles for kids. Then we share math riddles for middle school kids, some of which may prove challenging for older students and adults. Next, we have math riddles for adults, a selection perfect for parties or to use as icebreakers at work. The article ends with sections on hard and tricky math riddles.

You might want to start with the easy ones in the first section and work up to the last section, building your skill as you go. Put your thinking caps on and get started!

Math Riddles for Kids

Riddles are fun for kids, but they can also be educational. Our collection of math riddles for kids provides a fun challenge perfect for the classroom, a day camp, or for family fun. Some are easy and some provide even the smartest kid a challenge.

• Which month has 28 days?
  Show answer
  All of them
• What number goes up and doesn’t come back down?
  Show answer
  Your age
• If there are 4 apples and you take away 3, how many do you have?
  Show answer
  Three apples
• If eggs are $0.12 a dozen, how many eggs can you get for a dollar?
  Show answer
  100 eggs, at one penny each
• How did the soccer fan know before the game that the score would be 0-0?
  Show answer
  The score is always 0-0 before the game.
• How many sides does a circle have?
  Show answer
  Two – the inside and the outside
• If you buy a rooster for the purpose of laying eggs and you expect to get three eggs each day for breakfast, how many eggs will you have after three weeks?
  Show answer
  None, because roosters do not lay eggs.
• If two’s company and three’s a crowd, what are four and five?
  Show answer
  9
• If you multiply this number by any other number, the answer will always be the same. What number is this?
  Show answer
  Zero
• If it took 6 people 9 hours to build a barn, how long would it take 12 people to build the same barn?
  Show answer
  None, because the barn is already built.
• What is the next number in the series? 7,645 5,764 4,576
  Show answer
  6,457 because the last number is moved to the front to make the next number in the series.
• Tom was asked to paint the apartment number on plates for 100 apartments which means he will have to paint numbers 1 through 100. How many times will he paint the number 8?
  Show answer
  20 times (8, 18, 28, 38, 48, 58, 68, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 98)
• A farmer has 17 sheep and all but 9 die. How many are left?
  Show answer
  Nine
• What weighs more, a pound of iron or a pound of feathers?
  Show answer
  Both would weigh the same.
• If you can purchase 8 eggs for 26 cents, how many can you buy for a cent and a quarter?
  Show answer
  Eight
• What did one math book say to the other math book?
  Show answer
  Do you want to hear my problems?
• What did the triangle say to the circle?
  Show answer
  You’re pointless.
• What is the maximum possible number of times you can subtract number 5 from number 25?
  Show answer
  Only once, is because when you subtract 5 from 25, it becomes number 20, then 15, etc.

Math Riddles for Middle School

Middle school kids know all of the basic math facts and are beginning to use them to logically solve math problems and riddles. Our selection of math riddles for middle school provide the perfect way to show a student’s ability to reason and use logical thinking.

• A 300 ft. train is traveling 300 ft. per minute and must travel through a 300 ft. long tunnel. How long will it take the train to travel through the tunnel?
  Show answer
  Two minutes because it takes the front of the train one minute and the rest of the train will take two minutes to clear the tunnel.
• A grandmother, two mothers, and two daughters went to a baseball game together and bought one ticket each. How many tickets did they buy in total?
  Show answer
  Three tickets because the grandmother is the mother of the two daughters who are mothers.
• Tom is in charge of shipping and he can place 10 small boxes or 8 large boxes into a carton. A total of 96 boxes were sent in one shipment. The number of small boxes was less than large boxes. What is the total number of cartons he shipped?
  
  Show answer
  11 cartons
  If a total of 96 boxes are shipped, then the large boxes in the cartons must be a multiple of 8, which means either 16 or 56 large boxes. Since there are more large boxes in the cartons then the small ones, the number of large boxes must be 56. The number of small boxes is reduced to 96 – 56 = 40. Therefore, the total number of cartons shipped can be figured out this way:
  56/8 + 40/10 = 7 + 4 = 11
  
• I am a three-digit number. My second digit is 4 times bigger than the third digit. My first digit is 3 less than my second digit. What number am I?
  Show answer
  141
• I add five to nine and get two. The answer is correct, but how?
  Show answer
  When it is 9 p.m., add 5 hours to it and you will get 2 p.m.
• When Josh was 8, his brother was half his age. Now that Josh is 14, how old is his brother?
  Show answer
  His brother is 10. Half of 8 is 4, so Josh’s brother is 4 years younger. When Josh is 14, his brother is still 4 years younger, so he’s 10.
• In an odd little town, was an odd little stream, with odd little fish in an odd little team. A stranger approached a local fisherman and asked him how much his odd little fish weighed. The odd little man replied, “All the fish in this stream weigh exactly 1/2 of a pound plus 1/2 of a fish. Isn’t that odd?” How many pounds does an odd little fish weigh?
  Show answer
  One
• Leon works at the aquarium. When he tries to put each turtle in its own tank, he has one turtle too many. But if he puts two turtles per tank, he has one tank too many. How many turtles and how many tanks does Leon have?
  Show answer
  One
• If the zookeeper had 100 pairs of animals in her zoo and if two pairs of babies are born for each and every one of the original animals, and then sadly 23 animals don’t survive, how many animals do you have left in total?
  Show answer
  977 animals (100×2 = 200; 200+800 = 1000; 1000-23 = 977)
• If you place three matches on a table then tell a friend to add two more matches to make eight, how can he do so?
  Show answer
  Make a Roman numeral five out of two matches and add it to the three to make a Roman numeral eight.
• There is a clothing store in Smithville. The owner has devised his own method of pricing items. A vest costs $20, socks cost $25, a tie costs $15 and a blouse costs $30. Using the method, how much would a pair of underwear cost?
  Show answer
  $45 because the pricing method consists of charging $5 for each letter required to spell the item.
• When Mitch was 6 years old, his little sister, Lila, was half is age. If Mitch is 40 years old today, how old is Lila?
  Show answer
  She is 37 years old.
• If X is an odd number, when a letter is taken away from X and it becomes even. Which is that number?
  Show answer
  Seven (Seven-S=Even)
• A man is twice as old as his little sister. He is also half as old as their dad. Over a period of 50 years, the age of the sister will become half of their dad’s age. What is the age of the man now?
  Show answer
  He is 50 years old.
• You are given 3 positive numbers. You can add these numbers and multiply them together. The result you get will be the same. Which are the numbers?
  Show answer
  1, 2, and 3
• I am a three-digit number. My tens digit is six more than my one’s digit. My hundreds digit is eight less than my tens digit. What number am I?
  Show answer
  193
• If seven people meet each other and each shakes hands only once with each of the others, how many handshakes will there have been?
  Show answer
  Twenty-one
• How can you take 2 from 5 and leave 4?
  Show answer
  Remove the 2 letters F and E from the word FIVE and you have IV.
• Using only addition, how can you add eight 8’s to get the number 1,000?
  Show answer
  888 +88 +8 +8 +8 =1,000
• What can you put between a 7 and an 8 so that the result is greater than a seven, but less than an eight?
  Show answer
  A decimal because 7.8 is greater than 7, but less than 8.

Math Riddles for Adults

Our math riddles for adults will provide a challenge for many of our readers. Take your time and think carefully; your first answer will probably be wrong if you are too quick. What appears to be the right answer frequently isn’t. Be careful!

• How many times does the long hand of the clock pass the short hand between midnight one day and midnight the following day? As both hands are together at the starting time of midnight this does not count as a pass.
  Show answer
  21
• How can you make the following equation true by drawing only one straight line: 5+5+5=550 Can you figure it out?
  Show answer
  There are two ways to do so:
  Draw a line on the first plus sign to turn it into a 4.
  Change the equal symbol to a crossed-out equal symbol which means “not equal to.”
• What number do you get when you multiply all of the numbers on a telephone’s number pad?
  Show answer
  Zero, because any number multiplied by 0 will always equal 0.
• You go to the doctor because you are ill, and he prescribes you with three pills and tells you to take them every half hour. How long do the pills last you?
  Show answer
  An hour because the first pill doesn’t take 30 minutes to take.
• Where can you add 2 to 11 and get 1?
  Show answer
  On a clock
• Once I’m 24. Twice I’m 20. Three times I’m inappropriate. What am I?
  Show answer
  The letter “X”
• In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half the lake?
  Show answer
  The patch doubles in size every day and so on the 47th day the patch will be half the size it is on the 48th day.
• An apple is 40 cents, a banana is 60 cents. and a grapefruit is 80 cents. How much is a pear?
  Show answer
  Forty cents, because the price of each fruit is calculated by multiplying the number of vowels by 20 cents.
• Anna wrote all the numbers from 300 to 400 on a piece of paper. How many times did she write the digit 3?
  Show answer
  She wrote it 120 times.
• How many bricks does it take to complete a building made of brick?
  Show answer
  Only one – the “last” one
• How many days are there in 4 years?
  Show answer
  The answer is 1461, because (365 x 4) + 1. One of the years is a leap year.
• A bat and a ball cost $1.10. The bat costs one dollar more than the ball. How much does the ball cost?
  Show answer
  The ball costs 5 cents, not 10 cents. If one dollar more than 10 cents is $1.10, then $1.10 + 10 cents is $1.20. Therefore, the ball costs 5 cents.
• Harry is 54 years old, and his mother, Anna, is 80. How many years ago was Anna three times the age of her son Harry?
  Show answer
  41 years ago
• You have accidently left out the plug and are attempting to fill the bath with both taps full on. The hot tap takes 6 minutes to fill the bath. The cold tap takes 2 minutes and the water empties through the plug hole in 4 minutes. In how many minutes will the bath be filled?
  Show answer
  2 minutes and 24 seconds
• The day before yesterday I was 21, and the next year, I will be 24. What day is my birthday?
  Show answer
  31st December, because it must be on the 1st of January, when I turned 22 and so 21 the day before. As it is now a new year, I will be 23 this year and so 24 next year.
• If it were two hours later, it would be half as long until midnight as it would be if it were an hour later. What time is it now?
  Show answer
  9 p.m.
• A man is walking down a street night at a constant pace. As he passes the street light, he notices that his shadow becomes longer. Does the top of his shadow move faster, slower, or the same when the shadow is longer than when it is shorter?
  Show answer
  This point maintains a constant speed, independent of the length of the shadow.

Hard Math Riddles

Put on your thinking caps! Many of these hard math riddles rely on your knowledge and remembrance of math facts. They are similar to the word problems you might have hated in middle and high school. Don’t despair; you can get the answer if you stop and think. A piece of paper, pencil, and a calculator may help with some of these.

• John, Mark, and Henry are three brothers. Interestingly, their current age is prime. What’s more interesting is that difference between their ages is also prime. How old are they?
  Show answer
  Mark is 2, John is 5, and Henry is 7. Age diff 7 – 2 = 5 is prime; 7 – 5 = 2 is prime; 5 – 2 = 3 is prime.
• Divide 20 by half and add 30, what do you get?
  Show answer
  Seventy, because 20 divided by ½ = 10 + 30 = 70.
• Joe has ten coins totaling $1.19. From these coins, he cannot make exact change for a dollar, half-dollar, quarter, dime, or nickel. What coins does he have?
  Show answer
  A half-dollar, a quarter, four dimes, and four pennies.
• There are twelve kids in a classroom. Six kids are wearing socks and 4 are wearing shoes. Three kids are wearing both. How many have bare feet?
  Show answer
  Five kids have bare feet.
• There are 25 red balls, 47 green balls. and 3 blue balls in a basket. There is a blind man. What is the minimum number of balls that the blind man has to pick to make sure that there are at least 2 balls of different colors?
  Show answer
  48 balls. There is a small chance he may pick up 47 green balls in a row.
• One is to three as three is to five and five is to four and four is the magic number. What is the pattern?
  Show answer
  letters in it. (If you try more numbers, they will always come back to the number four, so four is the magic number.)
• Nathan has 8 bricks. Seven of them weigh the same amount and one is slightly heavier. Using a balance scale, how can Nathan find the heavier brick in two weighings?
  Show answer
  First, he splits them in to piles of 3, 3, and 2 bricks. Then he weighs both groups of 3 with each other. If they balance, he knows the brick is one of the 2 not-weighed bricks and he can weigh them to find the heaver one. If the stacks of 3 bricks do not balance, he will weigh 2 of the 3 bricks. If they balance, he will know the brick left not weighed is heavier, or if they do not balance, he will find the heavier one.
• Sally and Sarah were preparing to have a water balloon fight. “No Fair” cried Sally, “You have 3 times as many as I do!” Sarah said “Fine!” and gave Sally 10 more balloons. “Still not fair!” argued Sally, “You still have twice as many as I do.” How many more balloons must Sarah give Sally for them to have the same number?
  Show answer
  Sarah must give Sally another 20 water balloons, giving them each 60. Sally started with 30 water balloons and Sarah with 90.
• Two travelers spend from 12 o’clock to 6 o’clock walking along a level road, up a hill, and back again. Their pace is 4 mph on the level, 3 mph uphill, and 6 mph downhill. How far do they walk and at what time do they reach the top of the hill?
  Show answer
  They walk 4 miles and reach the top of the hill at half past three.

Tricky Math Riddles

Our article ends with tricky math riddles to really get your brain going! These are fun to share with others, because few people have heard all of them and the first and most apparent answer is usually wrong. They work well at a party, because many of the answers generate laughter.

• Two people in front of two people, two people behind two people, and two people beside two people. How many people are there?
  Show answer
  Four
• A certain number has three digits. The sum of the three digits equals 36 times this number. Seven times the left digit plus 9 is equal to 5 times the sum of the two other digits. 8 times the second digit minus 9 is equal to the sum of the first and third. What is the number?
  Show answer
  324
• A duck was given $9, a spider was given $36, a bee was given $27. Based on this information, how much money would be given to a cat?
  Show answer
  $18 ($4.50 per leg)
• A man dies of old age on his 25th birthday. How is this possible?
  Show answer
  He was born on February, 29th.
• A nonstop train leaves Moscow for Leningrad at 60 mph. Another nonstop train leaves Leningrad for Moscow at 40 mph. How far apart are the trains 1 hour before they pass each other?
  Show answer
  100 miles (60+40)
• Add me to myself and multiply by 4. Divide me by 8 and you will have me once more. What number am I?
  Show answer
  Any number
• Can you arrange four nines to make it equal to 100?
  Show answer
  99+9/9 = 100
• I am a number with a couple of friends, quarter a dozen, and you’ll find me again. What am I?
  Show answer
  Three
• I am a three-digit number. My tens digit is five more than my one’s digit. My hundreds digit is eight less than my tens digit. What number am I?
  Show answer
  194
• I am four times as old as my daughter. In 20 years, I shall be twice as old as her. How old are we now?
  Show answer
  I am 40 and my daughter is 10.
• I asked a girl how old she was. She said, “In 2 years I will be twice as old as I was 5 years ago.” How old is she?
  Show answer
  12
• If you’re 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?
  Show answer
  You will never reach the door, because it will always be half the distance, no matter how small.
• In a pond, there are some flowers with some bees hovering over them. How many flowers and bees are there if both the following statements are true:
  If each bee lands on a flower, one bee doesn’t get a flower.
  If two bees share each flower, there is one flower left out.
  
  Show answer
  4 bees and 3 flowers
• Janie’s friends were chipping in to buy her a wedding shower present. At first, 10 friends chipped in, but 2 of them dropped out. Each of the 8 had to chip in another dollar to bring the amount back up. How much money did they plan to collect?
  Show answer
  $40 (10 at $4, or 8 at $5)
• There are several books on a bookshelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?
  Show answer
  9 books
• There are two ducks in front of two other ducks. And, there are two ducks behind two other ducks. There are two ducks beside two other ducks. How many ducks are there?
  Show answer
  4 ducks (in a square)
• What 3 positive numbers give the same result when multiplied and added together?
  Show answer
  1, 2, and 3
• What is the value of 1/2 of 2/3 of 3/4 of 4/5 of 5/6 of 6/7 of 7/8 of 8/9 of 9/10 of 1000?
  Show answer
  100
• When John was six years old, he hammered a nail into his favorite tree to mark how tall he was. Ten years later at age sixteen, John returned to see how much higher the nail was. If the tree grew by five centimeters each year, how much higher would the nail be?
  Show answer
  The nail would be at the same height since trees grow at their tops.
• When my father was 31 and I was 8. Now he is twice as old as me. How old am I?
  Show answer
  The difference in age is 23 years, so I must be 23 if my father is twice as old as me.

Well, there you have it; a comprehensive list of math riddles for just about everyone. At this point, you should either be feeling extremely intelligent, or ready to go back to elementary school math. However, remember you can use these math riddles on your friends and appear intelligent, because you already know the answers. Have fun!

Susan Box Mann

Susan majored in English with a double minor in Humanities and Business at Arizona State University and earned a Master’s degree in Educational Administration from Liberty University. She taught grades four through twelve in both public and private schools. Subjects included English, U.S. and world history and geography, math, earth and physical science, Bible, information technologies, and creative writing.

Susan has been freelance writing for over ten years, during which time she has written and edited books, newspaper articles, biographies, book reviews, guidelines, neighborhood descriptions for realtors, Power Point presentations, resumes, and numerous other projects.

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