Density is mass per unit volume and can be calculated using ρ = m/V. Use compatible units: kg/m³ or g/cm³; 1 g/cm³ equals 1000 kg/m³. Different particle masses and spacings affect density; the same mass can occupy different volumes. Example: Convert density 2.7 g/cm³ to kg/m³. 1 g/cm³ = 1000 kg/m³, so 2.7 g/cm³ = 2700 kg/m³. Use the stated equation and consistent units to obtain a numerical result, then check whether its size and direction fit the physical situation. Give a reason. Use evidence.