Round to a Given Number of Significant Figures

In this activity, we will round 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 above, 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

 

One significant figure:

7,450 rounds to 7,000

32 rounds to 30

35,900 rounds to 40,000

0.00448 rounds to 0.004

0.0000487 rounds to 0.00005

 

 

Two significant figures:

7,450 rounds to 7,500

32.5 rounds to 33

295 rounds to 300

35,900 rounds to 36,000

0.00448 rounds to 0.0045

0.0000401 rounds to 0.000040

 

 

Three significant figures:

7,450 rounds to 7,450

32.99 rounds to 33.0

35,910 rounds to 35,900

35,990 rounds to 36,000

0.004487 rounds to 0.00449

0.00004895 rounds to 0.0000490

 

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

Over to you.