The density of iron is 7.87 g/mL. What is the mass of a 2.00cm x 4.00cm x 1.00cm block of iron?

Volume of the block of iron
= (2.00 × 4.00 × 1.00) cm³

Density of the block
= 7.87 g/ml
= 7.87 g/cm³

Mass of the iron block
= Volume × Density
= [(2.00 × 4.00 × 1.00) cm³] × (7.87 g/cm³)
= 63.0 g (to 3 sig. fig.)