Riddles
If it took 6 people 9 hours to build a barn, how long would it take 12 people to build the same barn?
The barn is already built.
You are given three positive numbers. You can add these numbers and multiply them together. The result you get will be the same. What are the numbers?
1,2 and 3
Two fathers and two sons 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.
One of the 'fathers' is also a grandfather. Therefore the other father is both a son and a father to the grandson.
Jeff has $28.75. He purchased three cookies that cost $1.50 each, five newspapers that each cost $0.50, five flowers for $1.25 each, and used the remainder of the cash on a pair of sunglasses. How much were the sunglasses?
$15.50
If you multiply this number by any other number, the answer will always be the same. What number is this?
Zero
A 300 ft. train traveling 300 ft. per minute must travel through a 300 ft. long tunnel. How long will it take the train to travel through the tunnel?
Two minutes. It takes the front of the train one minute, and the rest of the train will take two minutes to clear the tunnel.
I am a three-digit number. My second digit is four times bigger than the third digit. My first digit is three less than my second digit. Who am I?
141
Using only addition, add eight 8s to get the number 1,000.
888 + 88 + 8 + 8 + 8 = 1,000. This is the kind of number riddle you can work out with times tables, or by simple logic. First, get as close to 1,000 as you can (888). From there, it’s easy to figure out the rest.
What is the answer to "If two’s Company, and three’s a Crowd, What are four and five?"
Nine
If seven people meet each other and each shake hands only once with each of the others, how many handshakes happened?
21
One brother says of his younger brother: “Two years ago, I was three times as old as my brother was. In three years’ time, I will be twice as old as my brother.” How old are they each now?
One way to solve this math riddle is to use even numbers: The older brother will be twice as old as his younger brother in three years’ time. This immediately rules out the older brother currently being 8, 11, and 14, so he must be 17, and the younger brother 7. Two years ago, they were 15 and 5 respectively, and in three years’ time, they will be 20 and 10.
What is the maximum possible number of times you can subtract number 5 from number 25?
Once because after you subtract 5 from 25, it becomes 20.
A farmer is trying to cross a river. He is taking with him a rabbit, carrots and a fox, and he has a small raft. He can only bring 1 item a time across the river because his raft can only fit either the rabbit, the carrots or the fox. How does he cross the river?
Take rabbit across and go back. Take fox across and go back across with rabbit. Take carrots across and leave them with fox. Go back and get rabbit
The ages of a father and son add up to 66. The father’s age is the son’s age reversed. How old could they be?
51 and 15 years old, 42 and 24 years old, or 60 and 06 years old
If the zookeeper had 100 pairs of animals in her zoo and two pairs of babies are born for each original animal, then sadly, 23 animals don’t survive. How many animals do you have left in total?
977 animals
A man dies of old age on his 25th birthday. How is this possible?
He was born on February 29th.
Can you arrange four nines to make it equal to 100?
99+9/9 = 100
if 2+2=44, 3+3=96, 4+4=168, 5+5=2510, then what is the value of 6+6?
3612, because 6+6=(6x6)(6+6)=3612
If a hen and a half lay an egg and a half in a day and a half, how many eggs will half a dozen hens lay in half a dozen days?
Two dozen. If you increase both the number of hens and the amount of time available four-fold (i.e., 1.5 times 4 equals 6), the number of eggs increases 16 times. 16 x 1.5 = 24.
Old Granny Adams left half her money to her granddaughter and half that amount to her grandson. She left a sixth to her brother, and the remainder, $1,000, to the dogs’ home. How much did she leave altogether?
She left $12,000. One half plus one quarter plus one-sixth equals eleven-twelfths. So, the remainder, $1,000, is one-twelfth of the whole, which must have been $12,000.
If 66 = 2, 999 = 3, 8=2, 0=1, 9696=4, 8123=2, 98=3 and 88=4, then what does 816982 equal?
Six
Add me to myself and multiply by 4. Divide me by 8 and you will have me once more. What number am I?
4(x+x)/8 = x, so x can be any number
Three friends are on a road trip, and they rent a triple room for a night. When they get to the hotel, they pay the fee of $30 and go up to their room. The porter brings up their bags and refunds them $5 because the hotel is running a weeknight special. The three friends each keep one of the dollars and give the porter a $2 tip. Later, they sit down to work out their expenses for the weekend and find they have a problem. They each paid $10 for the room and got $1 back each, making their contributions $9. Then they gave the porter a $2 tip. However, 9 times three is 27, plus two is $29. Where did the extra dollar go
The three friends’ math is wrong. They didn’t spend $29, they spent $27: $25 on the room, and $2 for the porter’s tip. The three remaining dollars were returned to them!
A small number of cards has been lost from a complete pack. If I deal among four people, three cards remain. If I deal among three people, two remain and if I deal among five people, two cards remain. How many cards are there?
There are 47 cards.
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?
324
(1. 7x+9=5y+5z) (2. 8y-9=x+z) (3. 36x+36y +36z=100x+10y+z)