In this section we will extend our multiplication to include decimals.
It helps to think of any number which includes a decimal part as a whole number which has been adjusted by dividing by 10, 100, 1000 etc.
For example: 
3.5 = 35 ÷ 10 0.8 = 8 ÷ 10 4.25 = 425 ÷ 100 
(a)  4.7  
(b)  0.3 

(c)  54.3 

Now we can think about questions which have decimal parts in a different way.
Look carefully at the examples below  each stage is explained in square brackets.
Example 1 :  3.5 × 19  
=  35 ÷ 10 × 19  [replace the 3.5 by 35 ÷ 10]  
=  35 × 19 ÷ 10  [we can ÷10 and ×19 in either order]  
=  665 ÷ 10  [35 × 19 = 665 using one of the methods in section 6.2]  
=  66.5 
Example 2 :  9.2 × 0.8  
=  92 ÷ 10 × 8 ÷ 10  [replace 9.2 by 92 ÷ 10 and replace 0.8 by 8 ÷ 10]  
=  92 × 8 ÷ 10 ÷ 10  [we can ÷10 and ×8 in either order]  
=  736 ÷ 10 ÷ 10  [92 × 8 = 736 using one of the methods in section 6.2]  
=  7.36 
Practice Question
Work out the answer to this question on paper and then click on
to see whether you are correct.
Question 1
Find the answers to the multiplications involving decimals below (but not using a calculator).