What is the purpose of the universal gravitation constant in Newton's law of universal gravitation

The formula for the force of gravity is

Force = G m₁ m₂ / R².

If the formula were

Force = m₁ m₂ / R², without any 'G',

then in SI units, a couple of 10-kilogram blocks, 1 meter apart,

would attract each other with forces of 100 newtons ... about

23 pounds!

And in English units, a couple of 12-pound bowling balls

1 foot apart would attract each other with forces of 144 pounds!

As I'm sure you've noticed, they don't.

The forces of gravity are proportional to the product of the masses

divided by the square of the distance, but they're not equal to that

expression. In order to make an equation from a proportion, you

need a constant in there, and that's what 'G' is for.