The density of an object is the mass divided by the volume i.e. `d=m-:v`` ` So if you already know the volume `v` and the density `d` you can calculate the mass by resolving the equation. `d xx v=m-:vxxv` so `m=d xx v`` `
Say I have a cube of material that is exactly 5 cubic cm, and its density is .9 g/cubic cm. I can find that the mass of the cube is .9 x 5 =4.5 g
You can use similar transposition to find any similarly related measures.