Mysterious Math

This problem can be solved by preschool children in five to ten minutes, by programmers in an hour and by people with higher education…well, check it yourself.

8809 = 6
7111 = 0
2172 = 0
6666 = 4
1111 = 0
3213 = 0
7662 = 2
9313 = 1
0000 = 4
2222 = 0
3333 = 0
5555 = 0
8193 = 3
8096 = 5
1012 = 1
7777 = 0
9999 = 4
7756 = 1
6855 = 3
9881 = 5
5531 = 0
2581 = ?

What is the missing number and why?

Two. The number is how many closed circles there are in the 4 digits. 0, 6 and 9 each have one, 8 has 2.

Posted in Brain Teasers

What Comes Next I S I T

What comes next in this series?

I S I T P N A A D L I I Y N ___

The letter A.

There are three separate series

1. Starting with the first letter and taking every third letter you get ITALY.
2. Starting with the second letter and taking every third letter you get SPAIN.
3. Starting with the third letter and taking every third letter you get INDIA.

Posted in Brain Teasers

What Has Hair and Leaks?

What has hair and leaks when something bad happens?

Your eye. Your eyelashes are the hair and when something bad happens, your cry.

Posted in Riddles
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1 2 3 4 5 6 7 8 9 = 100

This equation is incomplete: 1 2 3 4 5 6 7 8 9 = 100

One way to make it accurate is by adding seven plus and minus signs, like so.

1 + 2 + 3 – 4 + 5 + 6 + 78 + 9 = 100

How can you do it using only 3 plus or minus signs?

123 – 45 – 67 + 89 = 100

Posted in Brain Teasers

Fill With Empty Hands

What do you fill with empty hands?

Gloves.

Posted in Riddles

A Blarmy Bridge

A boat full of people goes under a bridge and when it comes out the other side not a single person is on it. How can this be?

All the passengers are married.

Posted in Brain Teasers

Rope Around The Earth

If a piece of rope was tightly wrapped around the earth and you added 3 feet to its length, how high could you uniformly raise it from the earth’s surface?

Just short of 6 inches.

Thanks to Nigel Coldwell for this one.

Posted in Brain Teasers

Cat-Related Phrases

What are these words or phrases, which contain the word cat?

A dreadful event (11 letters)
A robber who climbs walls (10 letters, 2 words)
A systematic list (7 letters)

Catastrophe
Cat Burglar
Catalog

Posted in Brain Teasers

Mixed Animals for $100

At the market you can buy a cow for $10, a pig for $1 and 8 hens for $1. How many animals would you need to buy to get 100 mixed animals for exactly $100?

7 cows, 21 pigs and 72 hens. The trick to this is finding the combination of cows and hens with the same cost and quantity since pigs are already equal. The magic combination is 7 cows and 72 hens, giving you 79 animals that cost $79 ($70 + $9). Then you just add 21 pigs to get to 100 animals.

Posted in Brain Teasers

The Quirky Fruit Stand

At a quirky fruit stand, an orange costs 18 cents, a pineapple costs 27 cents and a grape costs 15 cents. Using the same logic, how much does a mango cost?

A mango costs 15 cents. The logic is 3 cents per letter.

Posted in Brain Teasers