What number is a multiple of ten but not a power of ten?

A number that is a multiple of ten but not a power of ten is 20. This is because 20 can be expressed as 10 multiplied by 2, making it a multiple of ten. However, it cannot be expressed as (10^n) for any integer (n), which is the defining characteristic of powers of ten. Other examples include 30, 40, and 50.