Answer: the force will increase 16 times
Step-by-step explanation:
as the equation of the force is written, it's denominator is the distance squared

so the distance is reduced by a factor of 4 ,the equation becomes
![f = G\frac{m_(1).{m_(2)} }{{[r/4]}^(2) }](https://img.qammunity.org/2024/formulas/physics/college/31ddyemyzyea8lwe2ponby34liplwce7se.png)
now as the distance r is divided by 4 the complete equation is multiplied by 16.