A composite number, we remember, is a whole number (no decimals or fractions) that can evenly divide (again, into no fractions or decimals) into two numbers other than itself and 1 (sort of the opposite of a prime number).
So, 8 needs to be one of the two numbers. Pick another number--any whole number--and multiply it by 8. The result will be your composite number.
Two examples: 8 times 6 equals 48. This works as 48 divided by 8 equals 6, both of which are whole numbers other than 48. Another is 72, the product of 8 times 9.