Guide

ADDITION / SUBTRACTION of DECIMALS

To add or subtract decimals:

Align the decimal numbers vertically, with the decimal points lined up.

2. Add zeros at the end of some decimal numbers so that the decimals will be of the same length.

3. Add or subtract the digits and put the decimal point in the final answer.

Illustrative Examples

Get the sum of 8.25 and 4.105.

Solution:

8.25

+4.105 Align the decimal numbers vertically, with the decimal points lined up.

8.250

+4.105 Add zeros at the end of some decimal numbers so that the decimals will be of the same length.

8.250

+4.105 Add the digits (from right to left) and put the decimal point in the final answer.

12.355

2. Get the difference between 2.598 and 0.52.

Solution:

2.598

- 0.52 Align the decimal numbers vertically, with the decimal points lined up.

2.598

-0.520 Add zeros at the end of some decimal numbers so that the decimals will be of the same length.

2.598

-0.520 Add the digits (from right to left) and put the decimal point in the final answer.

2.078

MULTIPLICATION of DECIMALS

When multiplying decimal numbers, first ignore the decimal point and multiply the digits just like whole numbers. The resulting number must have as many decimal places as the total number of decimal places the two original decimals have.

Illustrative Example:

Multiply 5.45 by 1.2.

Multiply the numbers and ignore the decimal point.

5.45 This has 2 decimal places.

x 1.2 This has 1 decimal place.

1 0 9 0

+5 4 5

6.5 4 0 Therefore, the final answer must have three decimal places. Count three digits from the right and put the

decimal point.

DIVISION of DECIMALS

To divide decimal numbers:

1. Move the decimal point of the divisor (the second decimal) to the right until it becomes a whole number.

2. Move the decimal point in the dividend (the first decimal) to the right the same number of places you move the decimal point in the divisor.

3. Divide normally just like whole numbers using the new decimals obtained from Step 1 and 2 and put the decimal point to the final answer.

Illustrative Example:

Divide 32.95 by 0.5

Solution:

Step 1: Move the decimal point of the divisor (the second decimal) to the right until it becomes a whole number. We can move one decimal place to the right of 0.5 so that it becomes a whole number (which is 5).

Step 2: Move the decimal point in the dividend (the first decimal) to the right the same number of places you move the decimal point in the divisor.

Step 3: Divide normally just like whole numbers using the new decimals obtained from Step 1 and 2 and put the decimal point to the final answer.

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