The gravitational force between two objects is <u>directly</u> proportional to the products of the masses and <u>inversely</u> proportional to the square of the distance between them. It is known as Newton's law of gravitation.
In mathematical terms it is given by :
Where
M and m are two masses
r is the distance between them
G = universal gravitational constant
The value of G is a universal constant. Its value do not varies from one location to another.