When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

Its something that each of us devours,
Not just us but birds, beats, trees, and flowers,
Frets iron and nibbles steel,
Toil hard stones to meal,
Exterminates king, collapse town,
And blows the mountains down.

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

How much will a 38° angle measure when looked at under a microscope that magnifies ten times?

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

I am lying and I always lie. Tell me whether I am lying or telling the truth.

What comes
Once in a Year
Twice in a Month
4 times in a Week
6 times in a Day

It is a six-letter word.
The first four letters are me.
The second and last letters are the same.
The fourth second and last letter is payment.

Who is it?

The average age of 10 members of a committee is the same as it was 4 years ago, because an old member has been replaced by a young member. Find how much younger is the new member ?

What came first, the chicken or the egg?