How many atoms in 5.5 moles? How many moles is 4.6 x 10^24 sulfur atoms? We'll solve problems like these, where we convert back and forth between moles and the number of atoms or molecules that we have. We'll be using both a common sense approach, and also a standard conversion factor method. We'll learn how to use a scientific calculation to do this math, and we'll see how to round our answers with scientific notation and significant figures.