If something is "to the power of 15" then it means it is multiplied by itself 14 times (one less than 15 as the original number is already to the power of 1).
An example:
So 2 to the power of 15, which we write as 215 = 2 * 2 * 2 * 2 etc... (so we have 15 written 2's in total meaning we will make 14 multiplications) is equal to 32,768.
