What is the biggest number in the

There isn't any "biggest".

If you ever meet anybody who tells you that he has the biggest number
in the world, ask him to let you see it, and when he does, take it and add
 ' 1 ' to it.  Then YOU'll have a number that's bigger than HIS number, and
that proves that his was not the biggest.

Some people say the answer is infinity, but since there is no such thing as infinity (I've learned that in one of my math classes last year), there is no such thing as the BIGGEST number in the world :)

Do your own homework