A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

Can you find out the missing number in the grid?

Can you place six matchsticks in a manner that each of the matchsticks is in touch with the other five matchsticks?

Can you write down eight eights so that they add up to one thousand?

A donkey is behind another donkey
I'm behind that second donkey
But there is a whole nation behind me

It is a murder you can describe in a word.

How many triangles are there on the puzzle below?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.