39 Math Riddles To Test Your Intelligence
Maths is one of those subjects you either loved or hated at school. And of those who loved working out math riddles and equations, it was only because the answers came easy to them. For the rest of us, maths is a subject that contains too many questions about fractions, positive numbers, and all manner of math brain teasers that have no room in the real world.
But these days maths problems have become popular logic puzzles people solve in games like Sudoku to keep the mind ticking over. Math games are seen by many as fun and a great way of testing your intelligence. While reading from a math book in high school trying to find the correct answer for your next pop quiz is still frowned upon by most students, adults are all about these challenging math riddles. If you fall into that category, then you are going to enjoy what we have collected below.
Searching far and wide we’ve gathered together an assortment of math games for you to try and solve. Whether you want to try and solve an easy math riddle, a tricky math riddle, a hard math riddle, or a fun math riddle, you’ll find something below that fits the bill. Suitable for all ages, these math riddles will test your skills and demonstrate how hard you studied while at school.
39 Math Riddles To Test Your Intelligence
Easy Math Riddles
1. Riddle: If there are four apples and you take away three, how many do you have?
Answer: You took three apples, so you have three.
2. Riddle: Using only addition, add eight 8s to get the number 1,000.
Answer: 888 + 88 + 8 + 8 + 8 = 1,000. This is the kind of number riddle you can work out with times tables, or by simple logic. First, get as close to 1,000 as you can (888). From there, it’s easy to figure out the rest.
3. Riddle: Two fathers and two sons sat down to eat eggs for breakfast. They ate exactly three eggs, each person had an egg. The riddle is for you to explain how.
Answer: One of the “fathers” is also a grandfather. Therefore the other father is both a son and a father to the grandson.
4. Riddle: Eggs are 12 cents a dozen. How many eggs can you get for a dollar?
Answer: 100 eggs for a penny each.
5. Riddle: How can you add eight fours together so the total adds up to 500?
Answer: 444 + 44 + 4 + 4 + 4 = 500.
6. Riddle: One brother says of his younger brother: “Two years ago, I was three times as old as my brother was. In three years’ time, I will be twice as old as my brother.” How old are they each now?
Answer: The older brother will be twice as old as his younger brother in three years’ time. This immediately rules out the older brother currently being eight, 11, or 14, so he must be 17, and the younger brother seven. Two years ago, they were 15 and five respectively, and in three years’ time, they will be 20 and ten. Simple multiplication. We think.
7. Riddle: A 300 feet train is traveling 300 feet per minute must travel through a 300 feet long tunnel. How long will it take the train to travel through the tunnel?
Answer: Two minutes. It takes the front of the train one minute, and the rest of the train will take two minutes to clear the tunnel.
8. Riddle: I add six to eleven, and get five. Why is this correct?
Answer: This numbers riddle uses a bit of misdirection. Think of numbers in terms of time. When it is 11 am, adding six hours makes it 5 pm.
9. Riddle: If seven people meet each other and each shakes hands only once with each of the others, how many handshakes happened
Answer: 21.
10. Riddle: I am four times older than my son. In 20 years’ time, I will be twice as old as he is. How old are we now?
Answer: 40 and 10
Tricky Math Riddles
11. Riddle: I am a three-digit number. My tens digit is five more than my ones digit. My hundreds digit is eight less than my tens digit. What number am I?
Answer: 194
12. Riddle: A merchant can place eight large boxes or 10 small boxes into a carton for shipping. In one shipment, he sent a total of 96 boxes. If there are more large boxes than small boxes, how many cartons did he ship?
Answer: 11 cartons total. Seven large boxes (7 x 8 = 56 boxes) and four small boxes (4 x 10 = 40). 11 total cartons and 96 boxes total.
13. Riddle: In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?
Answer: The person was born in 2005 B.C. Therefore, he was 5 years old in 2000 B.C, 10 in 1995 B.C., and 15 in 1990 B.C.
14. Riddle: Old Granny Adams left half her money to her granddaughter and half that amount to her grandson. She left a sixth to her brother, and the remainder, $1,000, to the dogs’ home. How much did she leave altogether?
Answer: Adding one-half, one-quarter, and one-sixth tells us that the total is a fraction of twelfths (2+4+6=12). You can also think about it as 6/12, 3/12, or 2/12, which equals 11/12. If the remainder is $1,000, that must be one-twelfth, so the total is $12,000.
15. Riddle: What single digit appears most frequently between and including the numbers 1 and 1,000?
Answer: The most common digit is 1. Every number 1-9 appears exactly the same number of times in every ten numbers. But because we included the number 1,000, there’s an extra occurrence of the number 1. In total, the number 1 appears 301 times, and every other number appears 300 times.
16. Riddle: A cellphone and a phone case cost $110 in total. The cell phone costs $100 more than the phone case. How much was the cellphone?
Answer: $105 (not $110).
17. Riddle: If a hen and a half lay an egg and a half in a day and a half, how many eggs will half a dozen hens lay in half a dozen days?
Answer: Two dozen. If you increase both the number of hens and the amount of time available four-fold (i.e., 1.5 x 4 = 6), the number of eggs increases 16 times (16 x 1.5 = 24).
18. Riddle: I am a three-digit number. My second digit is four times bigger than the third digit. My first digit is three less than my second digit. Who am I?
Answer: 141.
19. Riddle: Tom was asked to paint numbers outside 100 apartments, which means he will have to paint numbers one through 100. How many times will he have to paint the number eight?
Answer: 20 times (8, 18, 28, 38, 48, 58, 68, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 98).
20. Riddle: Robert and David played several golf matches against each other in a week. They played for a pizza at each match, but no pizzas were purchased until the end of the week. If Robert and David had the same number of wins at any time, those pizzas were canceled. Robert won four matches (but no pizzas), and David won three pizzas. How many rounds of golf were played?
Answer: 11. David won seven matches – four to cancel out Robert’s four wins and three more to win the pizzas.
Hard Math Riddles
21. Riddle: You want to boil an egg for two minutes but you only have a three-minute hourglass, a four-minute hourglass, and a five-minute hourglass, how can you boil the egg for only two minutes?
Answer: Once the water is boiling, turn the three-minute hourglass and five-minute hourglass over. When the three-minute hourglass runs out, put the egg in the boiling water. When the five-minute hourglass runs out, two minutes have elapsed and it is time to take the egg out of the water.
22. Riddle: My twin lives at the reverse of my house number. The difference between our house numbers ends in two. What are the lowest possible numbers for our house numbers?
Answer: The lowest possible numbers for the houses are 19 and 91. The difference is 72.
23. Riddle: What can you put between a seven and an eight so that the result is greater than a seven but less than an eight?
Answer: A decimal because 7.8 is greater than seven but less than eight.
24. Riddle: Three friends are on a road trip, and they rent a triple room for a night. When they get to the hotel, they pay the fee of $30 and go up to their room. The porter brings up their bags and refunds them $5 because the hotel is running a weeknight special. The three friends each keep one of the dollars and give the porter a $2 tip. Later, they sit down to work out their expenses for the weekend and find they have a problem.
They each paid $10 for the room and got $1 back each, making their contributions $9. Then they gave the porter a $2 tip. However, 9 times three is 27, plus two is $29. Where did the extra dollar go?
Answer: They didn’t spend $29, they spent $27 – $25 on the room and $2 for the porter’s tip. The three remaining dollars were returned to them.
25. Riddle: A duck was given $9, a spider was given $36, and a bee was given $27. Based on this information, how much money would be given to a cat?
Answer: $18 ($4.50 per leg).
26. Riddle: You want to boil an egg for two minutes but you only have a three-minute hourglass, a four-minute hourglass, and a five-minute hourglass, how can you boil the egg for only two minutes?
Answer: Once the water is boiling, turn the three-minute hourglass and five-minute hourglass over. When the three-minute hourglass runs out, put the egg in the boiling water. When the five-minute hourglass runs out, two minutes have elapsed and it is time to take the egg out of the water.
27. Riddle: I have a calculator that can display ten digits. How many different ten-digit numbers can I type using just the 0-9 keys once each, and moving from one keypress to the next using the knight’s move in chess? (In chess, the knight move in an L-shape — one square up and two across, two squares down and one across, two squares up and one across, and other like combinations).
Answer: You can form the numbers 5034927618 and 5038167294. You can also form their reverses: 8167294305 and 4927618305. Hence four different numbers can be made. The key point is to realize that the number must start or end on the “5” key, followed/preceded by the “0” key, otherwise, there is no way of using all ten keys during the route.
28. Riddle: Mrs. Jones was very proud of her apple tree. One autumn, after harvesting her apples, she called her three sons together. “Here are 150 apples,” she said. “I want you to take them to the market tomorrow and sell them for me.” She gave Paul 15 apples, Nick 50, and Ben 85. “Your job,” added Mrs. Jones, “is to sell the apples in such a way that each of you brings home the same amount of money.” How do they do it?
Answer: The first buyer purchases 12 dozen apples at $1 per dozen. Paul sells him one dozen and has three apples left; Nick sells him four dozen and has two apples left; Ben sells him seven dozen and has one apple left. Then a second buyer comes along and buys all their remaining apples for $3 apiece. The three brothers head home with $10 each.
29. Riddle: A small number of cards have been lost from a complete pack. If I deal among four people, three cards remain. If I deal among three people, two remain and if I deal among five people, two cards remain. How many cards are there?
Answer: There are 47 cards. Remember there are 52 cards in a pack. Find the multiples of four, three, and five closest to that number, and see if any of them are the same. For example, you can deal 42, 44, and 48 cards amongst four people, which would mean 9, 5, or 1 cards are missing (with three remaining). However, the only one that works for multiples of three and five people is when five cards are missing, which gives us a total of 47 cards.
Animal Math Riddles
30. Riddle: When asked about the animals on his farm, the farmer says: “I only ever keep sheep, goats, and horses. In fact, at the moment they are all sheep bar three, all goats bar four, and all horses bar five.” How many does he have of each animal?
Answer: The farmer has three sheep, two goats, and one horse. We know that there are three animals that are goats and horses, so we suppose there are two goats and one horse. This gives us three sheep, which works out because there are four non-goats: three sheep, and one horse.
31. Riddle: There are 100 pairs of dogs in a zoo; a pair of babies are born for each dog. Unfortunately, 23 of the dogs have not survived. How many dogs are left in total?
Answer: 977 dogs (100 x 2 = 200; 200 + 800 = 1,000; 1,000 – 23 = 977).
32. Riddle: If a hen and a half lay an egg and a half in a day and a half, how many eggs will half a dozen hens lay in half a dozen days?
Answer: Two dozen.
33. Riddle: A farmer has 19 sheep on his land. One day, a big storm hits, and all but seven run away. How many sheep does the farmer have left?
Answer: Seven. All but seven ran away.
34. Riddle: If you buy a rooster to lay eggs and you expect to get three eggs each day for breakfast, how many eggs will you have after three weeks?
Answer: None. Roosters don’t lay eggs.
Brain Teaser Math Riddles
35. Riddle: When I take five and add six, I get eleven, but when I take six and add seven, I get one. What am I?
Answer: A clock.
36. Riddle: If you go to the movies and you’re paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?
Answer: It’s cheaper to take two friends at the same time. In this case, you would only be buying three tickets, whereas if you take the same friend twice you are buying four tickets.
37. Riddle: 81 x 9 = 801. What must you do to make this equation true?
Answer: Flip it upside down. 108 = 6 x 18.
38. Riddle: If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again.
Answer: There is a 50/50 chance of each toss being either heads or tails. The previous toss does not impact the next toss.
39. Riddle: Which weighs more, 16 ounces of soda or a pound of solid gold?
Answer: Neither. They both weigh the same.
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