As , multiplying by is the same as multiplying by three times. That means you have to move the point three places to the right.
When you multiply a number by , you move the point in the number three places to the right.
If the number you want to multiply by isn’t a decimal number, remember that there’s always an invisible point behind the last digit in the number. By moving that point three places to the right, you get three empty places, and in each of those you put a .
The trick of moving the decimal point when multiplying by 10, is similar to a trick you can use when dividing by 1000.