Rounding

Rounding is the act of approximating numbers by ignoring everything after a given place value. This can sometimes make it easier to do mental calculations.

Rounding Whole Numbers

Usually, you will be asked to round to the nearest unit, ten, hundred or thousand.

Steps :-

  1. Write down the number to be rounded.
  2. Underline the required place to round to.
  3. Look at the number to the right of this:-

If it is 5 or more, increase your underlined digit by 1.
If it is less than 5, leave your underlined digit alone.

  1. Write out your number, as far as the underlined digit.
  2. Fill out any spaces with a zero.
  3. Include brackets showing what the number has been rounded to - eg( nearest ten).


Do not add any other numbers

Examples

 

round

 

round 100

round 1000

Practise

Rounding Decimals

This is very similar to rounding whole numbers, but the counting starts at the decimal point.

  1. Write down the number to be rounded.
  2. Count out the required number of decimal places to the right of the decimal point.
  3. Underline this figure.
  4. Look at the number to the right of this:-

If it is 5 or more, increase your underlined digit by 1.
If it is less than 5, leave your underlined digit alone.

  1. Write out your number, as far as the underlined digit.
  2. Include brackets showing what the number has been rounded to - eg( 2 dp).

Do not add any other numbers

Examples

 

round1

round2

3

4

quest

 

Practise

Significant Figures

This is very similar to rounding decimals, but the counting starts at thefar left.

  1. Write down the number to be rounded.
  2. Ignoring leading zeroes, start at the first digit and count out the required number of figures.
  3. Underline this figure.
  4. Look at the number to the right of this:-

If it is 5 or more, increase your underlined digit by 1.
If it is less than 5, leave your underlined digit alone.

  1. Write out your number, as far as the underlined digit.
  2. Fill in zeroes as place holders, as far as the decimal point.

Include brackets with the number of significant figures shown.

Do not add any other numbers

 

Examples

8

9

10

11

 

Tolerance

Tolerance is the limits to which a measurement applies.

Examples

14

12

13

15

 

 

© Alexander Forrest