Question

what is density please tell me how

Answer 1

Density is the mass per unit volume
Density = mass / volume

Answer 2

The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume:[1]