Question 69484
Natural numbers are numbers you would use to count things in the room, for example , and would be numbers like 1,2,3...etc. An integer is any whole number, so -2 is an integer but you wouldn't use it to count as a natural number. 

The constant {{{pi}}} is a perfect example of an irrational number, a number that cannot be represented rationally (in other words fractions), since the number goes on forever. However, {{{pi}}} is still a real number, but it's certainly not rational. Hope this helps.