Multiply Decimals Using Multiplication Facts

In this activity, we will learn to use simple multiplication facts to allow us to find answers to decimal multiplications.

Example

We can easily work out that 166 × 4 = 664  

So, can we use that to work out 166 x 0.04?

Answer

We know that 166 × 4 = 664

We can divide 4 by 100 to get 0.04, so we must also divide the 664 by 100 to give 6.64

So 166 × 0.04 = 6.64

Example 2

We can easily work out that 259 x 3 = 777

We can use that fact to find out 259 x 0.3

Answer

We know that 259 x 3 = 777 

We can divide 3 by 10 to get 0.3, so we must divide 777 by 10 to give 77.7

So 259 x 0.3 = 77.7

One useful tip is to check your answer makes sense!

Count how many decimal places there are in both the calculation and the answer. There should be the same number of decimal places in both.

E.g. 0.004 x 53 has three decimal places, so the answer must have three decimal places too: 0.212.  It does!

Now it's your turn to have a go.