Hoe does the force of gravitation between two objects change when the distance between them is reduced to half?

Explanation

`d = (1)/(2)`
F = `(m_(1)m_(2))/(d^(2) = (m_(1)m_(2))/((1)/(4) x)^(2)`
F = `(m_(1)m_(2))/((1)/(4)x^(2))`
Force is increased by four times.