Round Numbers to One or Two Significant Figures

In this activity, we will be rounding to a given number of significant figures.

 

The key thing to remember is to look at the digit to the right of the required number of significant figures.

If that digit is 5 or more, it rounds up and if it is below 5, it rounds down.

 

Look at the following examples.

 

The significant figures are shown in red. 

The other zeros are there as place holders, to make sure the size of the number is correct

e.g. 7,000 not 7

 

 

Example 1

One significant figure:

 

7,450 rounds to 7,000

32 rounds to 30

35,900 rounds to 40,000

0.448 rounds to 0.4

 

Example 2

Two significant figures:

 

7,450 rounds to 7,500

32.5 rounds to 33

285 rounds to 290

35,900 rounds to 36,000

0.453 rounds to 0.45

 

Now let's consolidate your understanding by attacking some questions.