Numbers are rounded to estimate answers using approximate answers.
Example 1
137x33= 3000
137= 100 to 1 significant figure
33=30 to 1 significant figure
100x30= 3000
137x33 is approximately 3000
Example 2
5130
_________
3.5 x 30.1
(Round to 1 significant figure)
It would be:
5000
_______ = 37,500
4x30
Rounding decimal places
When rounding to 1 decimal place look at the second decimal place.
Example:
10.865
When you want to round this to 1 sig-fig you look at the second number after the decimal place.
Draw a line to help you remember
10.8|65
• If the number is 4 or below you keep the number in the first decimal place the same.
• If the number is 5 or above you round the number in the first decimal place up.
10.865 rounded to 1d.p would be 10.9.
To round to 2 sig-figs you look at the third decimal place.
Example:
23.56870 rounded to 2d.p = 23.57
23.56|870
