What is the longest word in the dictionary?

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.

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

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

This is a simple one. You just have to count the number of Fs in the given sentence.

Finished Files are the result of years of scientific study combined with the experience of years.

How many did you count?

No one wants to have it, but if one got it, he does not want to lose it. What is It?

How can you make number one disappear by adding something to it?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

The doctor prescribed you to take one pill from the bottle every half an hour. The bottle is now left with only three pills.

How long do you think you have before you run out of pills?

There’s a one-story house in which everything is yellow. Yellow walls, yellow doors, yellow furniture. What colour are the stairs?