I need to solve a problem that I cannot figure out how to get the correct answer. Here is the problem: There is a face centered cubic with a density of $8\mathrm{.}95$ g$/$cm$.$ The goal is to find the radius of a Cu atom in picometers. The molar mass given is $63\mathrm{.}54$ g$/$ mol. I need to see step by step how the equation is completed so I can see where my error is$.$ The answer is $128$ picometers. Please show the stoichiometry that shows the units cancelling out with each step.