The Closure Property states that for a particular set of numbers, if you perform an operation (like addition or multiplication) on any two numbers from that set, the result will also be a number that belongs to the same set.
In this case, the product of 45 and 15 is
Since both 45 and 15 are integers, and the product of two integers is also an integer, we can conclude that the type of number resulting from the product of 45 and 15 is an integer.