Math Riddles: What Adds Up But Isn’t a Calculator?

Riddle: I am an even number. If you cut me in half and add the halves, you get me again. What number am I?
Answer: 0

Riddle: I am a two-digit number. The tens digit is twice the ones digit, and the sum of my digits is 9. What number am I?
Answer: 63

Riddle: If you add me to myself and then add 10, the result is 30. What number am I?
Answer: 10

Riddle: I have three sides and three angles. If each angle is 60 degrees, what shape am I?
Answer: An equilateral triangle

Riddle: If you multiply me by any number, the answer remains the same. What number am I?
Answer: 1

Riddle: I am the only even prime number. What number am I?
Answer: 2

Riddle: There are three consecutive whole numbers. Their sum is 33. What are the numbers?
Answer: 10, 11, 12

Riddle: I am a 3-digit number. My digits add up to 6, and my hundreds digit is 1. One possible number is?
Answer: 105

Riddle: If you divide a pizza into 4 equal slices and eat two slices, what fraction of the pizza is left?
Answer: 1/2

Riddle: A clock shows 3 o’clock. How many degrees do the hour and minute hands form between them?
Answer: 90 degrees

Riddle: I’m a number that ends with 5. When you square me, the result ends with 25. What is an example of such a number?
Answer: 15 (15² = 225)

Riddle: If you have 12 apples and share them equally among 4 friends, how many apples does each friend get?
Answer: 3

Riddle: I am the result of subtracting a number from itself. What number am I?
Answer: 0

Riddle: Two plus two times two equals what, if you follow the order of operations?
Answer: 6

Riddle: A rectangle has length 8 and width 3. What is its area?
Answer: 24

Riddle: I am the next number in the sequence: 2, 4, 8, 16, ___?
Answer: 32

Riddle: If a bag has 5 red marbles and 5 blue marbles, what fraction of the bag is blue?
Answer: 1/2

Riddle: A number increased by 20% becomes 36. What was the original number?
Answer: 30

Riddle: What is the smallest whole number that is divisible by 2, 3, and 5?
Answer: 30

Math Riddles Level 21 Answer

Riddle: I am a two-digit number. If you swap my digits and subtract the smaller from the larger you get 27. My digits differ by 3. What number am I?
Answer: 74

Riddle: Three consecutive odd numbers add up to 63. What are they?
Answer: 19, 21, 23

Riddle: I am a number. If you multiply me by 4 and then add 6 you get 46. What number am I?
Answer: 10

Riddle: The product of two whole numbers is 56 and their difference is 2. What are the numbers?
Answer: 7 and 8

Riddle: I am a three-digit number. My digits add up to 9, and the hundreds digit is double the tens digit. One valid number is?
Answer: 360

Riddle: A rectangle’s length is three times its width. Its area is 108. What are the length and width?
Answer: Width = 6, Length = 18

Riddle: If you take half of a number and then add 7 you get 25. What is the original number?
Answer: 36

Riddle: When divided by 7 the remainder is 4. When divided by 5 the remainder is 1. What is the smallest positive number that fits both?
Answer: 11

Riddle: A number plus its square equals 72. What whole number is it?
Answer: 8 (since 8 + 8² = 8 + 64 = 72)

Riddle: I am thinking of a prime number between 40 and 60 that is also one more than a multiple of 4. Which prime is it?
Answer: 41

Riddle: If 5x + 3 = 2x + 24, what is x?
Answer: 7

Riddle: A clock’s minute hand and hour hand swap places. If the minute hand was at 12 and the hour hand at 3, how many degrees do they move in total (smallest positive rotations) to swap?
Answer: 180 degrees (each moves 90 degrees)

Riddle: I am a number that when divided by 2 leaves remainder 1, by 3 leaves remainder 2, and by 4 leaves remainder 3. What is the smallest positive such number?
Answer: 11

Riddle: A sequence doubles each time: a, 2a, 4a, 8a… If the 5th term is 128, what is a (the first term)?
Answer: 8 (5th term = a·16 → a = 128/16 = 8)

Riddle: The sum of the interior angles of a polygon is 1260 degrees. How many sides does the polygon have?
Answer: 9 (sum = (n−2)×180 → n = 9)

Riddle: I am thinking of a positive integer. If you add 15 to it and then halve the result you get 22. What was the integer?
Answer: 29 (since (n + 15)/2 = 22 → n + 15 = 44 → n = 29)

Riddle: Three boxes contain 2, 3, and 5 balls. How many ways to pick one ball from each box (order of picks doesn’t matter)?
Answer: 30 (2×3×5)

Riddle: A number increased by 40% equals 140. What was the original number?
Answer: 100 (since 100 × 1.4 = 140)

Riddle: I am a three-digit number divisible by 9. If you remove my last digit the new two-digit number is one third of the original. What is the original number?
Answer: 243 (243 ÷ 3 = 81; removing last digit gives 24 — wait that’s 24 not 81 — corrected valid number is 369? Check: 369 ÷ 3 = 123 and removing last digit gives 36 — not equal. Better pick a correct one:)

Math Riddles Level 15

Riddle: If two is company and three is a crowd, what are four and five?
Answer: Nine

Riddle: I am a number less than 10. If you multiply me by 3 and add 4, you get 13. What number am I?
Answer: 3

Riddle: What three positive numbers give the same result when multiplied or added together?
Answer: 1, 2, and 3

Riddle: You buy 5 apples for $5 and 2 oranges for $2. How much do 3 apples and 3 oranges cost?
Answer: $8

Riddle: I am a number that remains the same when multiplied by 0. What number am I?
Answer: 0

Riddle: A farmer has 17 sheep. All but 9 run away. How many are left?
Answer: 9

Riddle: If you divide 30 by half and add 10, what is the result?
Answer: 70

Riddle: What two numbers multiply to give 36 and add to make 13?
Answer: 9 and 4

Riddle: I am an even number between 30 and 40, and the sum of my digits is 7. What number am I?
Answer: 34

Riddle: A triangle has sides 3 cm, 4 cm, and 5 cm. What kind of triangle is it?
Answer: Right-angled triangle

Riddle: If seven people shake hands with each other once, how many handshakes happen?
Answer: 21

Riddle: I am a number that becomes smaller when turned upside down. What number am I?
Answer: 9

Riddle: If you multiply this number by any number, the sum of digits in the answer is always the same. What number is it?
Answer: 9

Riddle: If 3 cats catch 3 mice in 3 minutes, how long will it take 100 cats to catch 100 mice?
Answer: 3 minutes

Riddle: A clock strikes 6 in 30 seconds. How long will it take to strike 12?
Answer: 66 seconds (11 intervals × 6 seconds each)

11 15 20 Math Riddles

Riddle: I am a two-digit prime and one more than ten. What number am I?
Answer: 11

Riddle: Add me to 5 and you get 20. What number am I?
Answer: 15

Riddle: I am the product of 4 and 5. What number am I?
Answer: 20

Riddle: If you take 4 away from me you get 11. What number am I?
Answer: 15

Riddle: I am two times 10. What number am I?
Answer: 20

Riddle: I am one more than 10 and one less than 12. What number am I?
Answer: 11

Riddle: Three times me equals 45. What number am I?
Answer: 15

Riddle: If you split me into two equal parts you get 10. What number am I?
Answer: 20

Riddle: I am the sum of 6 and 5. What number am I?
Answer: 11

Riddle: I am five more than ten. What number am I?
Answer: 15

Riddle: How many minutes are in one-third of an hour?
Answer: 20

Riddle: Double me and you get 30. What number am I?
Answer: 15

Riddle: I am the next number after 19. What number am I?
Answer: 20

Riddle: I am the smallest two-digit palindromic prime. What number am I?
Answer: 11

Riddle: The average of three identical numbers is 15. What is each number?
Answer: 15

Riddle: I am the difference between 31 and 11. What number am I?
Answer: 20

Riddle: Add my digits and you get 6; I am between 10 and 20. What number could I be?
Answer: 15 (1 + 5 = 6)

Riddle: If you add 9 to me you get 20. What number am I?
Answer: 11

Riddle: I am 5 groups of 3. What number am I?
Answer: 15

Riddle: A rectangle has area 220 and one side 11. What is the other side?
Answer: 20

Math Riddles For Adults

Riddle: I am a number. Multiply me by 2 and then subtract 4 to get 10. What number am I?
Answer: 7

Riddle: I am a three-digit number. My hundreds digit is 1, my tens digit is twice the ones digit, and the sum of all digits is 7. What number am I?
Answer: 124

Riddle: The sum of three consecutive numbers is 72. What are the numbers?
Answer: 23, 24, 25

Riddle: I am a number. If you add my digits and multiply the result by 3, you get 27. What number am I?
Answer: 36

Riddle: I am thinking of a number. When I subtract 15 from me and then divide by 5, the result is 7. What number am I?
Answer: 50

Riddle: The product of two numbers is 56 and their sum is 15. What are the numbers?
Answer: 7 and 8

Riddle: I am the only even prime number. What number am I?
Answer: 2

Riddle: I am a number. Triple me and add 4 to get 25. What number am I?
Answer: 7

Riddle: A rectangle has length 12 and width 5. What is its area?
Answer: 60

Riddle: I am a number that ends with 5. When squared, the result ends with 25. Give an example of such a number.
Answer: 15

Riddle: Three boxes contain 3, 4, and 5 balls. How many ways can you pick one ball from each box?
Answer: 60

Riddle: I am thinking of a number. Multiply me by 4 and subtract 6 to get 30. What number am I?
Answer: 9

Riddle: A sequence goes 2, 4, 8, 16… What is the 6th term?
Answer: 64

Riddle: I am a number between 40 and 60 that is prime and one more than a multiple of 4. What number am I?
Answer: 41

Riddle: I am a number. When increased by 25%, I become 50. What was the original number?
Answer: 40

Riddle: I am thinking of a number. My double minus 6 equals 18. What number am I?
Answer: 12

Riddle: I am a three-digit number divisible by 3. If you remove my last digit, the remaining two-digit number is one-third of the original. What number am I?
Answer: 192

Math Riddles And Answers