Let us assume that we are talking about graviational force of attraction.

** F = G M1 M2 / d² **

F is the force that one object pulls the other towards itself.

Here M1 = mass of 1st particle M2 = mass of second particle

d = distance between the two particles.

G = 6.67 * 10^-11 units [exponential -11]

This force is very less for small masses and significant for planets like Earth, Sun, moon etc.

Now, if d becomes d / 2, substitute it in the equation above, to get

F = G M1 M2 / (d/2)² = G M1 M2 / ( d² / 4 ) = GM1 M2 *4 / d²

= 4 * [G M1 M2 / d²]

__So the Force has become 4 times the previous value.__

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If we are talking about force between electric charges, then also the same result will be observed. The new value of force will be 4 times the original value.