Universal gravitation - radius?

[Mirole]

Using F = G * (m₁*m₂)/(r²)

We know that

G = 6.6673x10^-11 N*m²/kg²
m1(earth) = 6x10²⁴ kg
m2(moon) = 7.4x10²² kg
the Earth and moon are an average of 3.9x10⁸m apart

would r² be [3.9x10⁸]² or [3.9x10⁸ / 2]²?

-Thanks!

 

[Doc Al]

Why would you divide the distance in half?

 

[Ali Inam]

Here we are using radius...!
So, the first one is correct.

Here the distance between the two bodies mean the distances from their centres.
So, definitely, they are mentioning the radius