If you say my name, I will no longer exist. What am I?

If you go to the movies and you're paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?

What does this rebus riddle mean?

What has 88 keys?

Can you find the key in the picture below?

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

Akbar summoned Birbal out of anger.
He told him that he will have to face death.
He asked him to make a statement and if the statement is true he will be buried alive and if the statement is false, he will be thrown at lions.
After hearing Birbal’s statement, Akbar could do nothing but smile.
He gave him 5 gold bars and let him go.

What did Birbal say?

Can you find out the remainder when 3^300 is divided by 5?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

Give it food and it will live; give it water and it will die.