A student calculates the density of an unknown solid. The mass is 10.04 grams, and the volume is 8.21 cubic centimeters. How many significant figures should appear in the final answer?
Density = mass
So you are multiplying two numbers. When multiplying, the number of significant figures is determined by the number with the least number of significant digits. The volume has 3 significant figures. The mass has four significant figures (remember to count "sandwiched" zeros). Because volume has the lowest number of significant figures, that is the number of significant figures in the final answer. The answer is three.