The density of iron is 7.87 g/mL\rm g/mL. What is the mass of a 3.00cmcm ×\times 4.00 cm ×\rm cm~ \times 1.00 cm\rm cm block of iron?

The density of iron is 7.87 g/mL. What is the mass of a 3.00cm × 4.00 cm  1.00 cm block of iron?

is this what you mean?

The density of iron is 7.87 g/cm^3. What is the mass of a 3.00cm × 4.00 cm x 1.00 cm block of iron?

Volume=12cm^3

 

$$\\\frac{7.87g}{cm^3}\times \frac{12cm^3}{1}\\\\
=\frac{7.87*12g}{cm^3}\\\\
=94.99g$$