Riddle: How can you cut a cheese round into 8 pieces with only three cuts?
Answer: First you cut the cylinder lengthwise. With the two pieces stacked end to end, you cut the cheese into quarters with two cuts. The result is three cuts and 8 pieces of cheese. See the image below for three cuts needed to divide a cheese round into eight pieces.
Riddle: Adored by few, Feared and hated by many. Mistress of the entire universal reason, Master in the art of numbers. Some may have solved many of your mysteries, But there still much of them to find. What are they?
Answer: Mathematics.
Riddle: Taking that internship in a remote mountain lab might not have been the best idea. Pulling that lever with the skull symbol just to see what it did probably wasn't so smart either. But now is not the time for regrets because you need to get away from these mutant zombies...fast. Can you use math to get you and your friends over the bridge before the zombies arrive? Alex Gendler shows how.
Answer: At first it might seem like no matter what you do, you're just a minute or two short of time, but there is a way. The key is to minimize the time wasted by the two slowest people by having them cross together. And because you'll need to make a couple of return trips with the lantern, you'll want to have the fastest people available to do so. So, you and the lab assistant quickly run across with the lantern, though you have to slow down a bit to match her pace. After two minutes, both of you are across, and you, as the quickest, run back with the lantern. Only three minutes have passed. So far, so good. Now comes the hard part. The professor and the janitor take the lantern and cross together. This takes them ten minutes since the janitor has to slow down for the old professor who keeps muttering that he probably shouldn't have given the zombies night vision. By the time they're across, there are only four minutes left, and you're still stuck on the wrong side of the bridge. But remember, the lab assistant has been waiting on the other side, and she's the second fastest of the group. So she grabs the lantern from the professor and runs back across to you. Now with only two minutes left, the two of you make the final crossing. As you step on the far side of the gorge, you cut the ropes and collapse the bridge behind you, just in the nick of time.
Riddle: I am a three-digit number. All of my digits are prime. One of the numbers is even. Each of my numbers are used only once. The total of my first and last digits equals 10. The total of my first two digits equals 5.
Answer: This one is fairly easy if you use elimination if you follow all the first 5 steps you get three options: 525, 327, and 723 but if you followed the last step you would reach your answer. The answer was 327.
Riddle: A bottle costs a dollar more than a cork. Together they cost 110 cents. How much does the bottle cost and how much does the cork cost?
Answer: The right answer is that the bottle costs 105 cents, and the cork costs 5 cents.
Riddle: If someone says to you, "I'll bet you $1 that if you give me $2, I will give you $3 in return", would this be a good bet for you to accept?
Answer: No. This is a situation where you lose even if you win. Assuming the other person is being wise, they would take your $2 and say, "I lose", and give you $1 in return. You win the bet, but you're out $1.
Riddle: A professional fisherman caught 30 fish during a 5-day tournament. Each day, he caught three more fish than the day before. How many fish did the fisherman catch on the first day?
Answer: He didn't catch any fish the first day, but he caught 3 on the second day, 6 on the third day, 9 on the fourth day and 12 on the fifth day.
Riddle: The distance from the Earth to the Sun is about 100 million miles. The speed of light is 186,000 miles per second, and light takes eight minutes to reach the Earth from the Sun. Let's say the Sun rose at 6am this morning, and that by some freak of physics the speed of light is suddenly doubled to 372,000 miles a second.
What time will the Sun rise tomorrow?
Answer: 6am again. After all, what diffrence does the speed of light make to the answer? It's irrelevant- only the speed of the roation of the Earth matters here.
Riddle: What symbol can be put between 2 and 3 to make the result greater than 2 but less than 3?
Answer: A decimal point
Riddle: What two whole, positive numbers have the same answer when multiplied together as when one is divided by the other?
Answer: Any number and 1.
Riddle: In a pond, there are some flowers with some bees hovering over them. If both the following statements are true: 1. If each bee lands on a flower, one bee doesn't get a flower. 2. If two bees share each flower, there is one flower left out. How many flowers and bees are there?
Answer: 4 bees and 3 flowers.
Riddle: How many days are there in 4 years?
Answer: 1461, because one of the years is a leap year. 365 x 4= 1460 + 1= 1461
Riddle: A triangle has sides of 13, 18 and 31 inches. What is the triangle's area?
Answer: Zero. The two shorter sides of a triangle, when added together (13+18=31), must be greater than the third or longest side (31) for it to be a triangle by definition. Therefore, the result would be two parallel lines with an area of 0.
Riddle: Place three piles of matches on a table, one with 11 matches, the second with 7, and the third with 6. You are to move matches so that each pile holds 8 matches. You may add to any pile only as many matches as it already contains. All the matches must come from one other pile. For example, if a pile holds 6 matches, you may add 6 to it, no more or less.
You have three moves. How can you do it?
Answer: First pile to second; second to third; third to first:
| Pile | Initial number | First move | Second move | Third move |
| First | 11 | 11-7=4 | 4 | 4+4=8 |
| Second | 7 | 7+7=14 | 14-6=8 | 8 |
| Third | 6 | 6 | 6+6=12 | 12-4=8 |
Riddle: Jim was examining an angle measuring 14 and 1/2 degrees, using his magnifying glass that magnifies everything two times. Under the glass, how large would that angle measure?
Answer: 14 and 1/2 degrees. Explanation, angles remain constant when magnified. A square has 4-90 degree corners, if you zoom in (magnify) a square, it's still a square.
Riddle: The head of a whale is six feet long; his tail is as long as his head and half his body, and his body is half of his whole length. How long is the whale?
Answer: Forty-eight feet.
Riddle: King Tut died 120 years after King Eros was born. Their combined age when they died was 100 years. King Eros died in the year 40 B.C. In what year was King Tut born?
Answer: King Tut was born in 20 B.C. There were 120 years between the birth of King Eros and the death of King Tut, but since their ages amounted to only 100 years, there must have been 20 years when neither existed. This would be a period between the death of King Eros, 40 B.C., and the birth of King Tut, 20 B.C.
Riddle: At a children's party, 10 kids had juice, 8 kids had cake, and 6 kids had juice and cake.
How many kids were there at the party?
Answer: Tweleve kids. Six kids had juice and cake, leaving two out of the cake eaters that didn't have juice. As there were ten juicers, there must be twelve kids in total.
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 at any time Robert and David had the same number of wins, those pizzas were canceled. Robert won four matches (but no pizzas), and David won three pizzas. How many rounds of golf were played?
Answer: Eleven, David won 7 matches, 4 to cancel out Robert's 4 wins, and 3 more to win the pizzas.
Riddle: What is the smallest whole number that is equal to seven times the sum of its digits?
Answer: The answer to this math riddle is 21. You probably just guessed to answer this math riddle, which is fine, but you can also work it out algebraically. The two-digit number ab stands for 10a + b since the first digit represents 10s and the second represents units. If 10a + b = 7(a + b), then 10a + b = 7a + 7b, and so 3a = 6b, or, more simply, a = 2b. That is, the second digit must be twice the first. The smallest such number is 21.
