What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

What does this Rebus Picture means ?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

You bought me for dinner but never eat me. What am I?

When 99 is considered higher than 100?

If eleven plus two equals one, what does nine plus five equal?

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?

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?

The first person saw the bridge step on it and crossed,
the second person saw the bridge did not step on it but crossed,
the third person did not see the bridge did not step on it but crossed.
Who are these people?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?