Addition and Subtraction of Decimals

Additions and subtractions of decimals are carried out exactly in the same manner as whole numbers. However, you need to be very careful to set out your work correctly. Units must be under units, decimal points under decimal points, and so on.

Addition of Decimals:

Example:

0.2  +  0.6

Example 9.1.1:

Find the value of the following:

i) 18.5   +  32.5
ii) 4.38   +  1.56   + 23.781  
iii) 0.86   +  45   +  231.9  
iv) Find the sum of ₦24.90, ₦10.59 and ₦125.55

i) 18.5   +  32.5

Solution

ii) 4.38   +  1.56   + 23.781  

Solution

iii) 0.86   +  45   +  231.9  

Solution

iv) Find the sum of ₦24.90, ₦10.59 and ₦125.55

Solution

Subtraction of Decimals:

Example 9.1.2:

Find the difference between 289.46  and 181.24

Solution

The difference is 108.22

Example 9.1.3:

Reduce 72.19  by  39.98

Solution