how do you use sig fig when doing arithmetic operations?

Question

for some school related stuff that i need to know

Answer 1

When adding and subtracting, you are focusing on place value.  For example, if you are adding 14.323, which has 5 significant figures to say 101, which has three significant figures, your answer depends on the most restrict place value, rather than either the 3 or 5.  In this case, it's the 101, which only has digits to the one's place.  So while adding those two together on the calculator gives you 115.323, we must round to that one's place, and report only 115.

 

When multiplying and dividing, you give your result the same number of significant figures as your lower piece feeding into the result.  Using the same two numbers above but multiplying gives 1446.623 on the calculator, but we must round this to just 3 significant figures, or 1450, which is more easily seen as 3 when written as 1.45 x 10³.

 

Problems using more than one operation get more complex.