Unit Cell Volume

The smallest repeating unit of s crystal of table salt(the unit cell) is a cube with an edge of .0563nm. If the density of NaCl is 2.17 g/cm^3, what is the mass in grams of one unit cell?
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The edge of a unit cell in meters is:
1 nm = 1.00x10^-9m
Since 1 m = 100 cm = 10^2 cm,
(1.00x10^-9m)(10^2cm/m) = 1.000x10^-7 cm
The volume of a unit cell is:
(1.00x10^-7cm)^3 = 1.00x10^-21 cm^3

mass(unit cell) = (2.17 g/cm^3)(1.00x10^-21 cm^3) = 2.17x10^-21 g