Netwon's law of gravitation

Newton's law of Gravitation states that "the gravitational force between any 2 bodies is directly proportional to product of their masses and inversely proportional to square of the distance between  them from center of their masses."
Suppose  2 bodies each having their masses"m1" and "m2" and distance between them from center of their masses be "d" then according to Newton's law of gravitation
                                  Gravitational force between them (F)=(G.m1.m2)/d^2 gravitational constant(G):It is defined as force of attraction between 2 bodies of masses 1 kg each separated by distance of 1m from center of their body