Riddle: A frog fell into a well 12 feet deep. He could jump 3 feet, but every time he jumped 3 feet, he fell back 2 feet. How many times did he have to jump to get out of the well?
Answer: The tenth jump took him out. (On the tenth jump he reached 13 feet and was out.)
Riddle: You have 14 brown socks, 14 blue socks and 14 black socks in your sock drawer. How many socks must you remove (without looking to be sure) to have a matched pair?
Answer: Four. You will have a pair of one color or another.
Riddle: David is throwing Robert a surprise birthday party but he has to stay within his budget. He spent half of his money plus $2.00 on the cake. Half of what he had left plus $2.00 was spent on balloons and streamers. Then he spent half of what he had left plus $1.00 on candy. Now he is out of money, how much did he start with?
Answer: This one is best solved working backwards, the last part David spent half of what was left plus $1.00 on candy and then was out of money. That means he must have spent $2.00 on Candy as $1.00 was half of what he had using the same logic backwards: $2.00 on candy $6.00 on Balloons and Streamers $12.00 on the cake Total of $20.00.
Math Riddles
Riddle: 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?
Answer: This one is fairly easy - 324 is the answer.
Riddle: Why are 1999 ten pound notes worth more than 1993 ten pound notes?
Answer: Because there are more of them!
Math Riddles
Riddle: Two hours ago it was as long after one o'clock in the afternoon as it was before one o'clock in the morning. What time is it now?
Answer: It would be 9:00 pm. There are 12 hours between 1:00 pm and 1:00 am and half of that is six hours. Half-way between would be 7 o'clock. Two hours later it would be 9:00 o'clock.
Riddle: What is the 4 digit number in which the first digit is one-fifth of the last, and the second and third digits are the last digit multiplied by 3?
Answer: 1155.
Math Riddles
Riddle: Farmer Brown came to town with some watermelons. He sold half of them plus half a melon, and found that he had one whole melon left. How many melons did he take to town?
Answer: Three melons!
Riddle: You and your friend are trapped in a space prison on an alien planet. The alien warden decides to give you and your friend a chance at freedom. He states that your friend shall be allowed to temporarily leave your cell and try to escape through an electric gate guarded by a 3-number passcode. If your friend answers incorrectly or says anything but the final answer, your friend will be thrown back in the prison. A computer will then tell your friend 4 clues if requested. If this passcode is properly answered, you and your friend shall be freed. You are then blindfolded and your friend leaves. You hear your friend walk down one of the numbered hallways to the gate. Your friend asks for the first clue. A voice answers, "The numbers are in ascending order so that the number is greater than or equal to the number before it." Your friend asks for the second clue. The voice says, "The product of the 3 numbers is 36." Your friend asks for the third clue. The voice says, "The sum of the numbers is the number of the hallway you entered." Your friend pauses for a moment and thinks. Your friend then asks for the fourth and final clue. The voice says, "The largest number only appears once in the code." You hear a beep. You hear your cell door swing open. You are free! What was the code?
Answer: 2,2,9
Riddle: If place 1 cake of soap on a pan of a scale and 3/4 cake of soap and a 3/4-pound weight on the other, the pans balance. How much does a cake of soap weigh?
Answer: Since 1/4 cake weighs 3/4 pound, and entire cake weighs 3 pounds.
Riddle: A hundred stones are placed, in a straight line, a yard distant from each other. How many yards must a person walk, who undertakes to pick them up, and place them in a basket stationed one yard from the first stone?
Answer: In solving this question it is clear that to pick up the first stone and put it into the basket, the person must walk two yards, one in going for the stone and another in returning with it; that for the second stone he must walk four yards, and so on increasing by two as far as the hundredth, when he must walk two hundred yards, so that the sum total will be the product of 202 multiplied by 50, or 10,100 yards. If any one does not see why we multiply 202 by 50 in getting the answer, we refer him to his arithmetic.
Riddle: A half is a third of it. What is it?
Answer: 1 1/2.
Riddle: A woman went into a bank to cash an insurance refund check. By mistake the teller gave her dollars for cents and cents for dollars. She put the money in her purse but accidentally dropped a nickel on the floor. When she got home, she found that she had exactly twice the amount of the check she had cashed. She didn't have any money in her wallet before going to the bank. What was the exact amount of that check?
Answer: The amount must have been $31.63. She received $63.31. After she dropped a nickel there would remain the sum of $63.26, which is twice the amount of the check.
Riddle: When completed in 1889 the Eiffel Tower was something of a sensation. Designed by the French engineer Alexandre-Gustave Eiffel its height is 492 feet plus half its own height. How high is the Eiffel tower?
Answer: 984 feet.
Riddle: How many pluses should we put between the digits of 987,654,321 to get a total of 99, and where?
Answer: (6) 9 + 8 + 7 + 6 + 5 + 43 + 21= 99 (7) 9 + 8 + 7 + 65 + 4 + 3 + 2 + 1= 99  
Riddle: If 10 bags of jelly beans and 6 licorice sticks cost $1, and 10 licorice sticks and 6 jelly bean bags cost 92 cents. How much does one licorice stick cost?
Answer: 5 cents. Jelly bean bags cost 7 cents.
Riddle: Walking home one day, you take a short cut along the train tracks. The tracks cross a narrow bridge over a deep gorge. At the point you are 3/8 of the way across the bridge, you hear the train whistle somewhere behind you. You charge across the bridge, and jump off the track as the train is about to run you down. As it happens, if you had gone the other way, you would have reached safety just before being run over as well. If you can run ten miles per hour, how fast is the train moving?
Answer: The train is moving at 40 miles per hour. Imagine that a friend is walking with you. When the train whistle blows, you head away from the train, he heads toward it. When he reaches safety, you will be 6/8 (or 3/4)of the way across the bridge, and the train will have just reached the bridge. For the train to cross 4/4 of the bridge in the time you cross the remaining 1/4, the train must be moving four times your speed.
Riddle: Twelve flags stand equidistant along the track at the stadium. The runners start at the first flag. A runner reaches the eighth flag 8 seconds after he starts. If he runs at an even speed, how many seconds does he need altogether to reach the twelfth flag?
Answer: Not 12 seconds. There are 7 segments from the first flag tot the eighth, and 11 from the first to the twelfth. He runs each segment in 8/7 seconds; therefore, 11 segments take 88/7= 12 4/7 seconds.
Riddle: 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 are the coins?
Answer: A half-dollar, a quarter, four dimes, and four pennies.
Riddle: Given two 2s, "plus" can be changed to "times" without changing the results: 2 + 2= 2 x 2. The solution with three numbers is easy too: 1 + 2 + 3= 1 x 2 x 3. What is the answer for 4 numbers and for 5 numbers?
Answer: Solution for 4 numbers: 1 + 1 + 2 + 4= 1 x 1 x 2 x 4. Solution for 5 numbers: 1 + 1 + 1 + 2 + 5= 1 x 1 x 1 x 2 x 4  1 + 1 + 1 + 3 + 3= 1 x 1 x 1 x 2 x 4 1 + 1 +2 + 2 + 2= 1 x 1 x 2 x 2 x 2