please explain newton's inverse square rule step by step?

In physics, an inverse-square law is any physical law stating that some physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity. for example gravitational force of attraction between to bodies of mass m1 and m2 , according to this law the force of attraction is inversily proportion to square of the distance between them, suppose you increase the distance between the two bodies by 2 times than the force of attraction will going to decrease by 4 times.