Maths riddles and puzzles

Math Riddles

Try These Math Riddles (and visit again in the future to see additional riddles) and be sure to reach the bottom of this page to see my top picks for math riddles out there on the web:

1. Riddle of 8’s:
There are 8 8’s placed across the table, left to right. You are handed four plus signs to position at different spaces between the 8’s. Where would you place the plus signs so that the total is exactly 1000?

Answer: 888 + 88 + 8 + 8 + 8 = 1000

2. Two Mothers and Two Daughters Riddle:
Two mothers and two daughters 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 ‘mothers’ is also a grandmother. Therefore the other mother is both a daughter and a mother to the granddaughter.
In other words, the one mother is both a daughter and a mother.

3. Digit Frequency:
What digit is the most frequent between the numbers 1 and 1,000 (inclusive)? To solve this riddle you don’t want to manually do all of the math but rather try to figure out a pattern.?

The digits 0 through 9 all follow the same pattern there is exactly 1 occurrence of each digit for every ten numbers.
For instance the digit 2 appears once between 10 and 19, at 12. And 2 appears once between, 30 and 39 at 32.
However, each of the digits 1 through 9 also appear in other numbers in the tens and hundreds place
Again, let’s look at 2 which appears in 20,21,22, 23, etc.. as well as 200,201, 202,203..
So to figure out how to answer this riddle you had to see what distinguishes the number 1? Only that we are including 1,000 which would be the first ‘1’ in a new series of ten! In other words, the digit 1 only has a single extra occurrence (301 occurrences) compared to 2 or 3 or 9 which each have exactly 300 occurrences.

4. I am a three-digit number (a):
My tens digit is one more than my ones digit. My hundreds digit is eight less than my tens digit. What number am I?

Answer: 198

5. I am a three-digit number (b):
My tens digit is five more than my hundreds digit. My ones digit is one-half the product of my hundreds and my tens digit, although no digit among the three digit is repeated.

Answer: 163

6. I am a three-digit number (c):
My ones digit is six more than my hundreds digit. My tens digit is the sum of my ones digit and my hundreds digit.

Answer: 187

7. Riddle of 7’s:
7 + 7 ÷ 7 + 7 x 7 – 7 =

Answer: 50

8. Single Digits:
What three different single digits give the same result when multiplied and added together?

Answer: 1, 2, and 3

9. Bookshelf:
There are several books on a bookshelf. If one book is the 3rd from the left and 5th from the right, how many books are on the shelf?

Answer: 7

10. Pair of Socks:
If you have 26 blue socks, 18 black socks, and 12 brown socks scattered across the room in the dark, how many would you have to grab to get a matching pair?

Answer: 4; once you grab four you will definitely have a matching pair.

11. The Hour Glasses:
If you have a six minute hour glass and an 8 minute hour glass, how can you accurately time ten minutes?

Answer: Start both hourglasses, then when the six minute hourglass has finished immediately flip it again. When the eight minute hourglass runs out the six minute hourglass has four minutes left, so flip it and it will last another two minutes, so the eight minutes plus two minutes will give you the accurate ten minutes.

12. 100 Meter Dash Rematch
Two boys, Kevin and Kyle, are running a 100 meter race against each other two times over the span of a week. In the first race, Kevin beats Kyle by 5 meters. Later that week, to make this fair, Kevin stands five meters behind the starting line. Assuming they run the same speed in their rematch, who will win this second race?

Answer: Kevin will win again. In the first race, Kevin ran 100 meters in the same time it took Kyle to run 95 meters. In the rematch, when Kyle is at the 95 meter mark, Kevin will also be there. Since Kevin is faster than Kyle, Kevin wins the race in the final 5 meters.

13. The Cell Phone
A cell phone and charger cost $110 in total. The cell phone costs $100 more than the charger. How much was the cell phone?

Answer: $105

14. My Son’s Age
If you take my son’s age and multiply it by one and a half times his age you get 24. How old is my son?

Answer: 4 (4 X 6 = 24)

15. How Big Is My Family?
Mother and father have four daughters, and each daughter has one brother. How many people are in the family?

Answer: Seven

16. How Old Are We?
I am four times as old as my son. In 20 years I will be twice as old as him. How old are we now?

Answer: My son is 10 and I am 40.

17. Count the Days:
How many days are there in 4 years?

Answer: (4 X 365) + 1 = 1461. One of the years is a leap year.

18. How Many of Us:
There are two fathers and two sons. They walk into the store at the gas station and each buys a power bar for 50 cents. The total for all power bars was $1.50. How is that possible?

Answer: There was a grandfather, a father, and a son.

19. Divide and Add:
Divide 30 by half and add 40—what do you get?

Answer: 100 (30 divided by ½ is 60, then add 40 to get 100)

20. Three Digits:
Name two different three digit numbers: My tens digit is four times as big as my ones digit, while my hundreds digit is three less than my tens digit. What are these two different three-digit numbers?

Answer: 582 and 141

21. How Long Ago?
James is 56 years old and his father is 82. How many years ago was James’ father three times his age?

Answer: 43 years ago, when James was 13 and his father was 39.

22. How Many Balls to Select?
There are 17 red balls, 25 green balls, and 3 blue balls in a basket. Now comes along 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?

Answer: 26 balls. There is a very small chance that he picks up 25 green balls in a row.

23. Getting Rich Making Your Bed:
Create this deal with your parents: You will make your bed every day for thirty days IF they will pay you 1 cent for the first day and for each day thereafter twice as much as the day before. If your parents agree, how much will they pay you for the thirtieth time that you make the bed?

Answer: Over half a billion dollars—to be exact: $536,870,912.00

24. How Many Tricycles?
In the schoolyard, there are 16 bicycles and tricycles. The total number of wheels is 39. How many tricycles are there?

Answer: 7 tricycles.

25. How Many Bills of Each?
Charlie has $80 in his piggy bank and 20 bills. If he has four more $1 bills than $5 bills and 2 more $5 bills than $10 bills, how many bills of each denomination does he have?

Answer: 4 $10 bills, 6 $5 bills, and 10 $1 bills.

Top Picks for Math Riddles

Homeschool Math (homeschoolmath.net): If you can ignore the advertisements for attention deficit medicines that are all over this site (seriously), you’ll find a huge amount of fun and lively math puzzles and problem-solving that will keep your little math genius eager to crank out the solutions for hours on end.
Riddles.tips (https://riddles.tips ): Now here’s a clean site—literally over a thousand riddles, categorized from easy to hard, plus special sections on math, logic, and “what am I” riddles. Very light advertising–no curveball sales pitches or obnoxious pushing of other products on this site.
Riddle Ministry (riddleministry.com ) : This site has over 1,300 riddles, with a good portion of them math riddles. But don’t stop at those. They have everything from detective riddles, famous riddles, funny riddles, short riddles, interview riddles and more.
Just Riddles and More (justriddlesandmore.com ) : This site boasts over 5,000 riddles, with categories like “illusions,” “fun stuff,” and “jokes.” They have hundreds of math riddles and puzzles to solve.
BrainDen.com (www.braindem.com ) : This site offers many sub-categories of math riddles, in to such areas as algebra, geometry, numbers & sequences, math brain teasers, and more. Tons of additional quizzes. There is even a section called, “I’m bored,” which ought to wake up anyone from their daily ennui.

Click on one of the topics below to discover the best sites for enlivening your child’s mind: