Statistics and Significant Figures

Here are some guidelines concerning numerical operations:

1. Sums and differences
A. The number with the fewest number of significant figures after the decimal place dictates the number of significant figures after the decimal. For example,
4.7 + 0.44346 + 0.34 + 94.3 = 99.7836 = 99.8
Since the fewest number of significant figures after the decimal place was one (i.e. to the tenths place) the sum is reported to the tenths place. Note that the total number of significant three because there are two significant digits before the decimal place.

B. When adding or subtracting numbers in scientific notation, make sure that each number is expressed to the same power of ten.