Define G (universal gravitational constant).

Explanation

`F=G=(m_(1)m_(2))/(r^(2)) therefore G=(Fr^(2))/(m_(1)m_(2))`.
If we taken `m_(1)=m_(2)="unit"` mass and r = unit distance, numerically, G = F , i.e., G (universal gravitational constant) represents the magnitude of the gravitational force of attraction between two unit masses, separated by a unit distance.