To find 10% of a number all you need to do is move the decimal to the left once. Explain why this is true

When dividing by 10, 100, 1000 and so on, move the decimal point to the left as many places as there are 0s. So when dividing by 10, move the decimal point one place, by 100 two places, by 1000 three places and so on. If there is no decimal point in the original number, then imagine it at the end of the number.