The correct answers are:
Real; rational; integer; whole; natural
Explanation:
Real numbers cover most of the numbers we work with; they contain everything except complex (imaginary) numbers.
Rational numbers are any numbers that can be written as a fraction. 15 can be written as 15/1, which is a fraction, so it is a rational number.
Integers include positive and negative numbers, but no decimals or fractions. 15 is a positive number with no decimal, so it is an integer.
Whole numbers are positive numbers from 0 up, with no fractions or decimals. 15 is a positive number with no decimal, so it is a whole number.
Natural (counting) numbers are positive numbers from 1 up, with no fractions or decimals. 15 is a positive number with no decimal, so it is a natural number.
