# Math Help - Easy addition/subtraction problem, but what are the sig figs! :(

1. ## Easy addition/subtraction problem, but what are the sig figs! :(

So my instructor is trying to get use familiar with significant figures and I can't figure this one out.

107.838 - 2.113x10^2 + 5.623x10^3

I have inputted 5519.538, and 5520. It keeps coming back with "incorrect significant figures". Please help!

Got it but don't know why. 5.520x10^3 is the correct answer, but how is that different from the 5520? I hate sig figs.

2. ## Re: Easy addition/subtraction problem, but what are the sig figs! :(

Hi NeedDirection,

By the wiki entry (Significant figures - Wikipedia, the free encyclopedia), "The significant figures (also known as significant digits, and often shortened to sig figs) of a number are those digits that carry meaning contributing to its precision."

In your provided expression, three digits follow each decimal point. So I think we need to express the answer with the same precision, i.e., three digits following the decimal point.