Category: Brain Teasers

A green glass door

A green glass door admits only certain objects. Apples and balls are allowed, but pears and bats aren’t. What determines whether an item can enter?


All words with a repeated letter are allowed. Green glass door, apple and ball.

Here comes my wife and daughter

Two men are standing on one side of a bridge and two women are approaching them. One of the men says, “Here comes my wife and daughter” to which the second man replies, “Here comes my wife and daughter”. If they have not married the same woman and the women aren’t pregnant, how is this true?


The men are widowers and married each others’ daughter.

Given these equations

Given these equations, what is the answer to the last one?
5 3 2 = 151012
9 2 4 = 183662
8 6 3 = 482466
5 4 5 = 202504
7 2 5 = ?


f(x,y,z) = 10000*(x*y) + 100*(x*z) + transpose_digits(x*y + y*z)

transpose_digits() just swaps the digits


What four weights?

What four weights can be used to balance from 1 to 30 pounds?


A=1, B=3, C=9 and D=17

1lb = A
2lbs + A = B
3lbs = C
4lbs = A + B
5lbs + A + B = C
6lbs + B = C

Full n Empty

There are six glasses in a row. The first three are full of water, and the next three are empty. By moving only one glass how can you make them alternate between full and empty?


Pour the water from the 2nd glass into the 5th glass.

Which room is safest for him?

A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven’t eaten in 3 years. Which room is safest for him?


The third room, since the lions would be dead.

An unusual paragraph

This is an unusual paragraph. I’m curious as to just how quickly you can find out what is so unusual about it. It looks so ordinary and plain that you would think nothing was wrong with it. In fact, nothing is wrong with it! It is highly unusual though. Study it and think about it, but you still may not find anything odd. But if you work at it a bit, you might find out. Try to do so without any coaching.


The letter e is the most common letter in the English language, yet it never appears in the entire paragraph.

Who was it?

A man was killed on Sunday morning. His wife found the body and called the police. The police arrived and questioned the chef, maid, butler, and gardener. Their alibis were:
Chef – making breakfast
Maid – getting mail
Butler – setting table
Gardener – watering plants
The police immediately arrested the criminal. Who was it and how did they know?


The maid. Mail isn’t delivered on Sunday.