How do you round an answer up to 3 significant figures ?
To round off an answer to 3 significant figures look at the fourth figure after the decimal point.
If C is greater than or equal to 5, increase the third digit after the decimal point by 1 while eliminating C, else eliminate C without making a change in the third digit after the decimal point.
As an illustration: 23.0145 would be rounded off to 23.015 while 23.0144 would be rounded off to 23.014
Once this is done, the number has been rounded off to 3 significant figures.