 # Significant figures are the important numbers to concentrate on

Significant figures are the ones which contribute to the value. The museum exhibited pictures of significant female figures who had contributed to our way of life over the last 100 years.

A digit is significant if it contributes to the value of a number:

0.000730                       The only significant figures are 7 and 3

30743                            The significant figures are all of them: 3, 0, 7, 4 and 3

6000                              The significant figures are all of them: 6, 0, 0 and 0

608                                The significant figures are all of them: 6, 0 and 8

## The order of significance

36736                           3 is the first significant figure, 6 is the second significant figure.

## Another illustration is:

0.00083124                8 is the first significant figure.

3 is the next significant figure.

This project must be read in conjunction with Mammoth Memory How to remember rounding.

Example 1

Make 373,158 correct to 1 significant figure.

What this really means is round 373,158 to 1 significant figure. So rounding rules apply.

373,158                        Round to 1 significant figure.

373,158                        Underline the digit (first significant figure)

373,158                        Look next door

7                                    It’s five or more so you must round up.

400,000                        3 becomes 4 and all the numbers to the right become zero.

373,158 correct to 1 significant figure = 400,000

Example 2

Correct 0.00346 to 1 significant figure.

What this really means is round 0.00346 to 1 significant figure so rounding rules apply.

0.00346                         Round to 1 significant figure.

0.00346                         Underline the digit (3 is the first significant figure).

0.00346                         Look next door

4                                     It’s not 5 or more. It’s four or less so IGNORE.

0.003                             Keep underlined number the same. Change all the numbers to the right to a zero.

0.00346 to 1 significant figure is 0.003

Example 3

What is 0.00068341 to 2 significant figures?

What this really means is round 0.00068341 to 2 significant figures. So rounding rules apply.

0.00068341                   Round to 2 significant figure.

0.00068341                   Underline the digit (8 is the second significant figure).

0.00068341                   Look next door

3                                      It’s not 5 or more. It’s four or less so IGNORE.

0.00068000                   Keep underlined number the same. Change all the numbers to the right to a zero.

0.00068341 to 2 significant figures is 0.00068

Example 4

Change 8.983 to 2 significant figures.

What this really means is round 8.983 to 2 significant figures so rounding rules apply.

8.983                              Round to 2 significant figure.

8.983                              Underline the digit (9 is the second significant figure).

8.983                              Look next door

8                                     It’s 5 or more. So you must round up.

9.0                                 9 becomes 10.

NOTE:

Add one to the previous column