Significant Figures

Significant figures are the figures that are known with certainty followed by the first uncertain figure.

When doing math with several numbers, the final answer should have the same number of significant figures as the number with the fewest significant figures.

How to Determine Significant Figures in Measurements
There are three rules to follow:

1) All non-zero figures are significant

2) All zeroes between significant figures are significant

3) Zeroes at the end of a number are only significant to the right of the decimal point.