10+10 and 11+11 can give you the same answer.

Explain how?

A boy and his father are caught in a traffic accident, and the father dies. Immediately the boy is rushed to a hospital, suffering from injuries. But the attending surgeon at the hospital, upon seeing the boy, says 'I cannot operate. This boy is my son.' How is this situation explained?

How many triangles are there on the puzzle below?

In a football game, Christina defeated Teresa by 2 - 0 but no man from either side scored. How can this be possible?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

Your job is to measure 45 minutes if you have only two cords and matches to light the cords.

1. The two cords are twisted from various materials, so their different segments can burn at different rates.
2. Each cord burns from end to end in exactly one hour.

Describe your way of measuring the 45 minutes.

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

The following question it puts forth you:

25 - 55 + (85 + 65) = ?

Then, you are told that even though you might think it's wrong, the correct answer is actually 5!

Whats your reaction to it? How can this be true?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?