What always comes into a house through the keyhole?

If a zookeeper had 100 pairs of animals in her zoo, and two pairs of babies are born for each one of the original animals, then (sadly) 23 animals don’t survive, how many animals do you have left in total?

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

If you're 8 feet away from a door and with each move you advance half the distance to the door. How many moves will it take to reach the door?

How can you throw a ball as hard as you can and have it come back to you even if it doesn't hit anything there is nothing attached to it and no one else catches or throws it.

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

Move three sticks of the spiral below to form a square.

An ape is trying to climb on a pole that is 60 feet high. Due to the slippery surface, the ape climbs 3 feet in a minute only to slip back 2 feet.

How much time do you think the monkey will take to reach the top of the pole?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

What is black when you buy it, red when you use it, and gray when you throw it away?