How will the force of the Coulomb interaction of two small charged balls change with an increase in the charge

How will the force of the Coulomb interaction of two small charged balls change with an increase in the charge of each of the balls by 2 times, if the distance between them remains unchanged?

Given:
Two balls;
Increase each of the balls by 2 times.
Find: change in the strength of the Coulomb interaction.
Decision:
In order to reveal what will be the relationship between the increase in balls and the Coulomb force, we write down the formula.
F = k * q1 * q2 / r ^ 2.
Here q1 and q2 will denote balls.
We write this formula again, but multiply the variables denoting balls by 2, as required in the condition. Then we get:
F1 = k * 2 * q1 * 2 * q2 / r ^ 2 = 4 * k * q1 * q2 / r ^ 2.
Now transformable by expressing F1 through F. Then it turns out that F 1 = 4 * F.
Hence it can be seen that after increasing the balls by 2 times, the force of the Coulomb interaction will be increased by 4 times.
Answer: will increase by 4 times