Question

State whether the following set is finite or infinite

A = {x : x is a multiple of 5, x ∈ N }

Answer 1

It is an infinite set as there are innumerable multiples of 5 like 5,10,15,20,25,..... and so on.

Answer 2

Multiples of 5 are 5,10,15,20.......
The ending limit is not given 
hence the set is infinite