Multiplying Decimals

The easiest way to multiply decimals is to first multiply each of them by whichever number (10, 100, 1000) is necessary to get rid of the decimal. Then we can multiply them together.

At the end we must divide the result by whatever we multiplied the parts by at the beginning (e.g. if at the beginning we multiplied one number by 10 and another number by 100, then at the end we must divide the result by 1000.

Examples

Exercise

Let’s complete exercise 7I from page 105 of the textbook:

The answers are below:

Dividing Decimals

Dividing decimals is actually easier than multiplying decimals, because we don’t need to end the process by “undoing” the multiplications we did at the beginning. As long as we have multiplied both of the numbers in our division by the same number (e.g. 10, 100, 1000), it will not affect the answers (because 100a/100b = a/b). Do make sure though that you are multiplying both of them by the same number.

Example

Exercise

Let’s complete exercise 7J from page 106 of the textbook:

The answers are below: