Decimal Places

Decimal places are used to express a number with greater precision by representing fractions as decimals. In this guide, we will explore the process of rounding off numbers to a specified number of decimal places and rounding to the nearest integer, as well as working with negative numbers and examples to demonstrate these concepts.

Rounding to a Specified Number of Decimal Places

When rounding a number to a certain number of decimal places, we can follow these rules:

1. If the digit immediately to the right of the rounding position is 0, 1, 2, 3, or 4, leave the rounding position digit unchanged.

2. If the digit immediately to the right of the rounding position is 5, 6, 7, 8, or 9, increase the rounding position digit by 1.

Examples:

  • 4.3612 = 4.36 (rounded to two decimal places)
  • 4.36539 = 4.365 (rounded to three decimal places)

Rounding to the Nearest Integer

Rounding to the nearest integer means rounding a number to zero decimal places. We can use the same rules as above:

Examples:

  • 567.123 = 567 (rounded to the nearest integer)
  • 4.019 = 4 (rounded to the nearest integer)

Working with Negative Numbers

When rounding negative numbers, it’s important to remember that the number line increases in value as you move to the right, so rounding may decrease the magnitude of a negative number.

Examples:

  • -123.456 = -123 (rounded to the nearest integer)
  • -123.678 = -124 (rounded to the nearest integer)

Practice Examples

Write the following numbers correct to 3 decimal places:

i) 1.23456

ii) 0.99998

iii) -14.0195

iv) 123.45602

v) 1000.0001

Rounded to 3 decimal places:

i) 1.235

ii) 1.000

iii) -14.020

iv) 123.456

v) 1000.000