Answer: Density
This measurement tells you how packed in a substance is. The higher the density, the more the object weighs for a certain volumetric unit (such as a cubic meter). Eg: a cubic meter of feathers is likely to weigh less than a cubic meter of solid gold because the feathers have a lot more air in them as opposed to the gold which is more compact.
density = mass/volume is the formula you often use
The multiplicative inverse of 6 1/8 (49/8) is
8/49
