Riddle: How can you make the following equation true by drawing only one straight line: 5+5+5=550? Can you figure it out?
Answer: Draw a line on the first plus sign that turns it into a 4! The equation then becomes true: 545+5=550. You could also change the equal symbol to a crossed out equal symbol which means "not equal to".
Riddle: In a certain city, 5% of all the people in town have unlisted phone numbers. If you select 100 names at random from that city's phone directory, how many people selected will have unlisted phone numbers?
Answer: None. If their names are in the phone directory, they do not have unlisted phone numbers!
Riddle: 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?
Answer: Infinity! Technically you will never reach the door, as you can only move half the distance, no matter how small.
Math Riddles
Riddle: What did the little lobster get on its math test?
Answer: Sea-plus.
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: Number 194.
Math Riddles
Riddle: How old is your son? asked a man to his neighbour. My son is five times as old as my daughter and my wife is five times as old as my son. Iam twice as old as my wife whereas my grandmother, who is celebrating her eighty-first birthday is as old as all of us put togeather. How old is the man's son?
Answer: Five.
Riddle: You have 6 eggs. You break 2, cook 2 and you eat 2 eggs. How many do you have left?
Answer: 4. The 2 you break are the ones you cook, which are the ones you eat.
Math Riddles
Riddle: A sphere has three, a circle has two, and a point has zero. What is it?
Answer: Dimensions.
Riddle: If 4+2=26, 8+1=79 and 6+5=111. Then, what is 7+3?
Answer: 410. 4+2=26 is because 4-2=2 and 4+2=6,so it is 26. Therefore, 7-3=4 and 7+3=10(410).
Riddle: A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?
Answer: Nine Years.
Riddle: What is the next number in the sequence? 2, 3, 5, 9, 17, _
Answer: 33. The pattern:  Double the previous number and subtract 1.
Riddle: Why is it easier to count cows than sheep?
Answer: You can use a cowculator.
Riddle: Find the four digit number in which the first digit is one fourth of the last digit, the second digit is 6 times the first digit, and the third digit is the second digit plus 3. What is it?
Answer: 1694.
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.
Riddle: In a stable there are men and horses. In all, there are 22 heads and 72 feet. How many men and how many horses are in the stable?
Answer: 14 horses and 8 men. 14x4 plus 8x2 = 72 feet.
Riddle: Something very extraordinary happened on the 6th of May, 1978 at 12:34 a.m. What was it?
Answer: At that moment, the time and day could be written as: 12:34, 5/6/78.
Riddle: When my father was 31 I was 8. Now he is twice as old as me. How old am I?
Answer: The difference in age is 23 years, so I must be 23 if my father is twice as old as me.
Riddle: What two whole, postive numbers have the same answer when multiplied together as when added together?
Answer: 2 and 2.
Riddle: What is the most useful instrument in a mathematics teacher's tool kit?
Answer: Multi-pilers!
Riddle: Take two numbers, such that the square of the first, plus the square of the second, shall equal 8; while the first, plus the product of the first and second, shall equal 6. What are the two numbers?
Answer: 2 and 2.