Math Riddles
Question: When is 99 more than 100?
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Question: What number do you get when you multiply all of the numbers on a telephone's number pad?
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Question: What 3 positive numbers give the same result when multiplied and added together?
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Question: Mr. Smith has 4 daughters. Each of his daughters has a brother.
How many children does Mr. Smith have?
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Question: You have been given the task of transporting 3,000 apples 1,000 miles from Appleland to Bananaville. Your truck can carry 1,000 apples at a time. Every time you travel a mile towards Bananaville you must pay a tax of 1 apple but you pay nothing when going in the other direction (towards Appleland).
What is highest number of apples you can get to Bananaville?
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Question: Mr. Smith has two children. If the older child is a boy, what are the odds that the other child is also a boy?
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Question: How can you add 8 8's to make 1000?
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Question: You have a glass of water that looks about half full. How can you tell, only using the glass of water itself, if the glass is half full or not?
The glass is a right cylinder.
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Question: There is a 5 gallon and a 3 gallon box. You also have a hose with unlimited water. How are you gonna make the 5 gallon have 4 gallons using your items? (You do not know the exact measure measurements of a gallon)
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Question: If 1/2 of 5 is 3, then what is 1/3 of 10?
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Question: Hard, Harder, and Hardest are brothers. By age from youngest to oldest, it goes Hard, Harder, Hardest. Hard is half the age of Hardest who is 20 which means hard is 10. Harder has a two-year difference between the number of years older he is than Hard and the number of years younger he is than Hardest. Harder is closer to the age of Hard than Hardest. How old is Harder?
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Question: In an apartment complex in New York there are one hundred married couples. When one of the husbands cheats on his wife with one of the other wives, his wife has no idea. With the large amount of gossip in the complex, all of the other wives know he is cheating. If a wife finds out that her husband is cheating on her, she kills him the following morning. Someone anonymously sends an email to all of the wives in the building saying that at least 1 man is cheating on his wife in the building.
How many husbands will be killed and how long will it take?
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Question: You have two coconuts and you want to find out how high they can be dropped from a 100 story building before they break. But you only have $1.40 and the elevator costs a dime each time you ride it up (it's free for rides down).
How can you drop the coconuts to guarantee you will find the lowest floor they will break at, while starting and ending at floor 1?
Note: They break when dropped from the same height and they don't weaken from getting dropped.
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Question: There is a chain nailed to the wall. The chain is 10 feet long and the center of the chain dips down 5 feet from where each side of the chain is nailed to the wall. How far are the 2 ends of chain from each other?
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Question: Four people need to cross a bridge in 17 minutes in the middle of the night. The bridge can only hold two or less people at any time and they only have one flashlight so they must travel together (or alone). The flashlight can only travel with a person so every time it crosses the bridge it must be carried back. Tom can cross in 1 minute, John can cross in 2 minutes, Sally can cross in 5 minutes, and Connor can cross in 10 minutes. If two people cross together they go as fast as the slower person.How can they cross the bridge in 17 minutes or less?
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Question: Does a ton of feathers or a ton of bricks weigh more?
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Question: A fast food restaurant sells chicken in orders of 6, 9, and 20.
What is the largest number of pieces of chicken you cannot order from this restaurant?
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Question: What is the next number in the sequence? 1 11 21 1211 111221 312211
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Question: Why are manholes round instead of square?
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Question: Does a pound of gold or a pound of feathers weight more?
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Question: Sum Sam and Product Pete are in class when their teacher gives Sam the Sum of two numbers and Pete the product of the same two numbers (these numbers are greater than or equal to 2). They must figure out the two numbers.
Sam: I don't know what the numbers are Pete.
Pete: I knew you didn't know the numbers... But neither do I.
Sam: In that case, I do know the numbers.
What are the numbers?
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Question: Five pirates are parting ways after finding a treasure of 100 pieces of gold. The pirates decide to split it based on a vote. Each pirate, from oldest to youngest, gets to propose a plan on how to split the gold.
If at least 50 percent of the other remaining pirates agree on the plan, that is how they will split the gold. If less than 50 percent of the pirates agree, the pirate who came up with the plan will be thrown overboard. Each pirate is smart, greedy, and wants to throw as many others overboard as possible without reducing the amount of gold they get.
What plan can the first (oldest) pirate propose to live and get as much gold as possible?
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Question: If you randomly choose one of the following answers to this question, what is your chance of getting it right?
A) 50%
B) 25%
C) 0%
D) 25%
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Question: A man in New York City has $10₹$. He spends $6.50₹$ on flowers, and $3₹$ on lunch (hot coffee and a hot dog). He then gets on the subway which will take him 7 stops for 50 cents. But he is forced to get off of the subway just 5 stops away from where he began.
Why is this?
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Question: What's the angle between minute hand and hour hand at a quarter past three?
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Question: John has some chickens that have been laying him plenty of eggs. He wants to give away his eggs to several of his friends, but he wants to give them all the same number of eggs. He figures out that he needs to give 7 of his friends eggs for them to get the same amount, otherwise there is 1 extra egg left.
What is the least number of eggs he needs for this to be true?
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Question: Little Johnny is walking home. He has $300₹$ he has to bring home to his mom. While he is walking a man stops him and gives him a chance to double his money. The man says "I'll give you $600₹$ if you can roll 1 die and get a 4 or above, you can roll 2 dice and get a 5 or 6 on at least one of them, or you can roll 3 dice and get a 6 on at least on die. If you don't I get your $300₹$."
What does Johnny do to have the best chance of getting home with the money?
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Question: There are two planes. One is going from New York to London at a speed of 600 MPH. The other is traveling from London to New York at a speed of 500 MPH.
When the planes meet which one will be closer to London?
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Question: There are several books on a bookshelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?
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Question: Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation.
Note: Each must be used exactly once and no other numbers or symbols can be used.
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Question: An ant gets onto one end of a tight rope that is 1 meter long. The ant is traveling at 1 centimeter per second, but the entire rope is being stretched an extra 1 meter (1,000 centimeters) a second (it can be stretched forever).
Will the ant ever reach the other end of the rope?
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Question: A hobo picks up cigarette butts from the ground and can make a cigarette with 4 butts. If he finds 16 cigarette butts, how many cigarettes can he make?
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Question: If you have an 11 minute and 13 minute hourglass, how can you accurately time 15 minutes?
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Question: Jasmine has a toaster with two slots that toasts one side of each piece of bread at a time, and it takes one minute to do so.
If she wants to make 3 pieces of toast, what is the least amount of time she needs to toast them on both sides?
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Question: Nathan has math 4 times a week. If he has math 8:00 Monday, 9:20 on Tuesday, 10:40 on Wednesday, and 1:20 on Friday, when does Nathan have math on Thursday?
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Question: What is 40 divided by 1/2, plus 15?
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Question: If 1+9+8=1, what is 2+8+9?
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Question: You have a large number of friends coming over and they all get thirsty. Your first friend asks for 1/2 a cup of water. Your second friend asks for 1/4 a cup of water. Your third friend asks for 1/8 a cup of water, etc.
How many cups of water do you need to serve your friends?
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Question: Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a sports car; behind all of the others is bicycles. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 2, revealing a bicycle. He then says to you, "Do you want to pick door No. 3?" Is it to your advantage to switch your choice?
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Question: John has been hired to paint the numbers 1 through 100 on 100 apartments.
How many times with he have to paint 8?
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Question: A man taking the census walks up to the apartment of a mathematician and asks him if he has any children and how old they are. The mathematician says "I have three daughters and the product of their ages is 72." The man tells the mathematician that he needs more information, so the mathematician tells him "The sum of their ages is equal to our apartment number." The man still needs more information so the mathematician tells him "My oldest daughter has her own bed and the other two share bunk beds."
How old are his daughters?
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Question: Tom wants to send Sally an expensive ring through the mail because they live thousands of miles apart. The only problem is that everything sent through the mail is stolen unless there is a lock put on it. Both Tom and Sally have plenty of locks and keys but they don't have any of the same locks or keys.
How can Tom send Sally the ring without it getting stolen?
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Question: It takes ten men ten hours to build a certain wall. How long does it take five men to build the same wall?
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Question: Two men find an old gold coin and want to have a coin toss with it to decide who gets it. The only problem is the coin is heavier on one side so it comes up heads more than tails. What is a fair way for the men to toss the coin and decide who gets the coin?
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Question: What does 1+1=.
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Question: If you have 30 white socks, 22 black socks, and 14 blue socks scattered across the floor in the dark, how many would you have to grab to get a matching pair?
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Question: There are 6 sisters. Each sister has 1 brother. How many brothers are in the sisters' family?
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Question: In a house of Kardak's family each brother have a sisters as double as their brothers and each sister have brothers as same as their sister. How many brothers and sisters in Kardak's family ?
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Question: A man wants to have a party in thirty-one days where he will be serving his 1000 barrels of wine. The only problem is that one of his enemies poisoned one of the barrels. The poison kills any man who drinks any of the wine in about 30 days, give or take a few hours. The man has 10 plants that are also killed by the poison in 30 days and can be used to test the wine. How can identify the single poisoned barrel of wine?
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Question: John has been hired to paint the numbers 1 through 100 on 100 apartments.
How many times with he have to paint 8?
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Question: What are the next two letters in the following series and why? WATNTLITFS__
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Question: A claustrophobic person gets on a train. The train enters a tunnel just as it is leaving the station.
Where is the best place for him to sit?
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Question: How many people do you need to have the odds be in favor (at least 50% chance) of two people having the same birthday?
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Question: What is the difference between a dollar and a half and thirty five-cents?
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Question: You have a bag with 'N' strings in it. You randomly grab two ends and tie them together until there are no more loose ends.
In the end, what is the expected number of loops (strings tied to their own end)?
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Question: What single line can you add to the following statement to make it true?
5+5+5=550
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Question: There are two ropes that both take exactly 1 hour to burn from end to end. You are unable to cut the rope. How can you burn the two ropes in a total of 45 minutes?
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Question: If you have two twins, three triplets and four quadruplets; how many people do you have?
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Question: If you toss a coin ten times and it lands heads up every time, what are the chances it will land heads up if you toss it again?
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Question: If 1+9+8=1, what is 2+8+9?
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Question: When is 1500 plus 20 and 1600 minus 40 the same thing?
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Question: A deaf and mute man goes to the train station. Tickets for the train are 50 cents each. The man goes to the ticket booth and hands the man inside just a dollar. The man in the booth hands him two tickets.
How did the man in the booth know to give him two tickets without even looking at him?
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Question: A farmer has three fields. One of them has 3 bundles of hay, another has 4, and the last has 5. How many would he have in the first field if he combined all of them in that field?
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Question: 2 men catch 2 fish in 2 minutes. At this rate, how many men could catch 500 fish in 500 minutes?
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Question: You have 7 tennis balls that are all identical but one of them is slightly lighter than the others.
Using a balance scale and only two separate weightings, how can you find the light tennis ball?
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Question: You have an 8 by 8 chess board that has two corner squares diagonal from each other removed. Is there any way to place 31 dominoes of size 2x1 to cover the remaining 62 spaces?
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Question: There are 100 coins scattered in a dark room. 90 have heads facing up and 10 are facing tails up. You cannot tell which coins are which. How do you sort the coins into two piles that contain the same number of tails up coins?
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Question: What is 1/2 of 2/3 of 3/4 of 4/5 of 5/6 of 6/7 of 7/8 of 8/9 of 9/10 of 10,000?
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Question: The warden of a circular jail is extremely hyper one day so he begins running around opening cells. The jail has 100 cells numbered from 1 to 100. He runs in a circle and opens all of the cells. Next he runs around and closes every 2nd cell (starting with cell 2, 4, 6 , etc.). If a cell is open he closes it and if a cell is closed he opens it. When he finishes running by all 100 cells he opens/closes every 3rd cell (starting with 3, 6, 9, 12 etc.), then every 4th cell (starting with 4, 8, 12, etc.) and so on. He does this until he goes around and only changes the 100th cell.
When he is done what cells will be open?
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Question: A shrimping boat is at the docks with a lifeboat hanging off the side 5 meters above the water. If the tides rise at a rate of 1.5 meters per hour, how long would it take for the water to reach the lifeboat.
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Question: Two boys, Trevor and Tyler, are running a 100 meter race. The first time they race Trevor beats Tyler by 5 meters. To make things fair, the next time they race Trevor stands 5 meters behind the starting line.
Who wins the second race (assuming they run the same speed as the first race)?
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Question: A man was born on January 1st, 23 B.C. and died January 2nd, 23 A.D. How old did he live to be?
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Question: A mother is 21 years older than her child. In 6 years the mother will be 5 times older than her baby.
Where is the father?
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Question: There are 100 passengers boarding a 100 passenger airplane. When passenger 1 gets onto the plane, he is dissoriented, so he randomly picks a seat. Each of the remaining passengers (2, 3, 4, etc.) get onto the plane and take their seat if it is available or picks one of the remaining seats at random if it is not.
What is the chance that the last passenger (passenger 100) will get his seat?
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Question: A grandfather has a broken grandfather clock that is off by a minute every hour (too fast). He figures out a way, while keeping it running at the same rate, to make the clock say the correct time twice a day.
How could he do this?
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Question: On a clock, how many times a day do the minute and hour hand overlap?
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Question: You have a bag with 'N' strings in it. You randomly grab two ends and tie them together until there are no more loose ends.
In the end, what is the expected number of loops (strings tied to their own end)?
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Question: Joe deals himself and his friend John some cards from a deck of cards (not the same amount). If John gives Joe some cards Joe will have 4 times as many cards as John. If Joe gives John the same number of cards he will have 3 times as many cards as John.
How many cards does each man have and how many cards do they trade?
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Question: You're going to a friends house and want to give them some brownies. On the way to their house you cross 5 bridges. At each bridge you must pay a toll of half of your brownies to the owner. But they are all very nice and give you back a brownie from what you give them.
How many brownies must you start with to give your friend 2 brownies?
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Question: A pond with dimension of 6m by 3m wil be filled of water lilies at exactly 30 days. Each day the number of water lilies will be doubled. First day 1, second day 2 etc... On what day it will fill half of the pond?
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Question: You have two buckets: one with only white marbles and one with only black marbles. The two buckets have the same number of marbles.
How can you rearrange the marbles to maximize your chances of grabbing a white marble from each?
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Question: Everyday a peasant must pay the king one pound of gold and leave it on a collection plate in front of his house. Every morning a guard comes by to make sure he has put a pound of gold on the plate. The king collects the gold every six days from the plate. If the peasant only has one six pound block of gold, how can he make only two parallel cuts and still follow the kings rules each day?
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Question: Sam has two sons named Nathan and Daniel, Daniel is exactly 5 years older than Nathan and Daniel was born on February 29th 1996. How old is Nathan?
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Question: If you have a cake, how many pieces of cake can you form with 3 straight cuts?
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Question: You have two books. One of them is upside-down and the other is rotated so the top of the book is facing you.
What is the sum of the first page in each book?
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Question: A knight comes to a castle where his love is trapped. The castle is surrounded by a square moat that is 10 feet wide (it forms a square around the castle). The knight is able to fashion two 9 foot long planks to cross the moat.
How can he do this?
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Question: What is half of 2+2?
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Question: You find me behind the stars; or in a sixth, seventh, or third.
It takes something round, a computer, and me to make pie.
I am bigger than anything you can think of.
What am I?
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Question: Two simple warriors: a vegetable and none. It depends on whether they work together to reduce infinity to one.
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Question: Which triangle will have a larger perimeter : 3,4,5 or 3,4,7 ?
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Question: 1 is 3, 3 is 5, 5 is 4, 4 is universal. 2 is 3, 3 is 5, 5 is 4, 4 is universal... how is this possible? (What is the rule to this sequence of numbers?)
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Question: Ants on a stick may only move left or right. If they bump into each other they bounce off of each other and immediately move in the opposite direction maintaining speed the entire time. The only time they change speed is when they fall off of the edge of the stick.
If 25 ants are randomly put on a 1 meter long stick moving 1 meter per second, what is the longest amount of time it could take for them to all fall off?
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Question: A smart landscaper is given the task of placing 4 trees so that they are all the same distant away from each other.
How does he do this?
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Question: A tomato vine is 3 meters long. The bottom foot of the vine doesn't grow any tomatoes but the rest of the vine grows a tomato every 5 inches.
How many vegetables can grow off of the vine?
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Question: You have a cube made of 10 x 10 x 10 smaller cubes, for a total of 1000 smaller cubes. If you take off 1 layer of cubes, how many remain?
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Question: Every time a man lies his nose grows to 150 percent of its size. Every time he tells the truth it shrinks to 50 percent of its size.
What will happen if he alternates between lies and the truth?
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Question: Can you find the missing number in the below series?
43, 8, 38, 9, 34, 11, _, 14
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Question: If a mountain climber climbed up a mountain one day from midnight to midnight the next day and does the same thing the following day when coming down the mountain, would there be a time at which he was at the same position on the mountain both day?
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Question: There are three jars full of equal amounts quarters, dimes, and penny's. Which one has the highest value?
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Question: If 4+5=24 7+2=21 9+6=63 6+7=?
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Question: Which is correct, 9 and 5 is 13 or 9 plus 5 is 13?
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