Question

Which of the following is a rational number?
8
15
44
45
π

Answer 1

All of them except pi. All of the other numbers can be written as fractions, (8/1),(15/1)(44/1) etc.

Answer 2

All of them are, except ' π ' (pi) ... which gives you an idea of why
that one is usually written as a symbol and not as digits.

Here's a useful factoid regarding the other numbers on the list:
-- ANY number that you can write down on paper, completely,
using digits, is a rational number.