What do we know:
- the dimensions ⇒ can help us find the volume, area, surface area
 - mass
 
What do we want to find ⇒ Density
To solve that,
 ⇒ must find the relationship between density, mass, and volume
- Definition of density: mass per unit volume
 
 ⇒ Density = mass / volume
Now let's convert some units to make it into a standard answer:
- mass = 100g ⇒ 0.1 kg (1000g = 1kg)
 - volume = 2 * 4 * 6 = 48 cubic centimeters = 0.000048 cubic meter
 
 (1 cubic meter = 1000000 cubic centimeter)
 
 ⇒ Density = 0.1 / 0.000048 = 2,083.33 kilograms per cubic meter 
Hope that helps!