A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

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?

A large container is kept in open under the rain. Every passing hour, the water collected inside the container becomes double what it was.

In ten hours, the container is filled completely. Can you calculate how long would it have taken to be filled in half?

Can you find the six hidden animals in the picture below?

What number do you get when you multiply all of the numbers on a telephone's number pad?

I went to the bookshop and spent one-half of the money that was in my purse.

When I came out, I found that I had as many cents as I had dollars and half as many dollars as I had cents when I went in. Find the money in my purse when I entered the store.

A container contains 100 eggs. They can be either fresh or rotten. What is sure is the fact that there is at least one fresh egg in that container.

If you are asked to pick two eggs randomly from the container, at least one of them will be rotten.

Can you calculate how many eggs in that container are fresh?

I can write cow in 13 letters.

Can You?

Our product and our sum always give the same answer. Who are we?