Addition and Subtraction of Decimals

The decimal number system is used to represent a number with a greater precision in comparison to integers or whole numbers. For example, when we have to divide 3 pies among 4 kids, we cannot represent the pies received by each kid in terms of integers alone, as each kid has received pies that lies between 0 and 1.

In order to deal with other similar problems, the concept of decimal was introduced. Thus, the concept of addition, multiplication, division and subtraction of decimals is an important topic. Let us say, two friends are contributing to buy cricket ball costing Rs 20. One of them has Rs 7.50 and the other has Rs 18.50. In order to know, how much money each will have to contribute and how much they will be left with, they must understand the concept of addition and subtraction of decimals.

Addition of Decimals

Addition in numbers is performed using the following steps:

  1. The numbers are first padded with zero depending upon the maximum digits present after the decimal for any of the numbers. For example, while adding 3.456 to 7.1, since the number 3.456 has more number of digits after the decimal, the padding is done according to 3.456. Since 3.456 have 3 digits after the decimal, we pad 7.1 to three places as 7.100.
  2. The numbers are lined up vertically along each other, as shown below

  1. Add the two decimals

Let us understand the concept more clearly with the help of the following examples:

Example 1: Addition 1.091 + 1.33:

Example 2: Addition 0.0075 + 5:

Subtraction of decimals

Subtraction in decimals is performed using the following steps:

  1. The numbers are first padded with zero depending upon the maximum digits present after the decimal for any of the numbers. For example, while subtracting 3.456 from 7.1, since the number 3.456 has more number of digits after the decimal, the padding is done according to 3.456. Since 3.456 have 3 digits after the decimal, we pad 7.1 to three places as 7.100.
  2. The numbers are lined up vertically along each other, as shown below

  1. Subtract

Let us understand the concept more clearly with the help of the following examples:

Example 1: Subtraction: 7.304 – 1.15

Example 2: Subtraction 4.1 – 0.94