In our physics class we were discussing about Coulomb's Law and equation for the electrostatic force between two points: $$F_{e}=\frac{Q_{1}Q_{2}}{4\pi \epsilon_0 r^2}$$
From the equation a query arose which is for what reason does the constant involve $4\pi$.
It's just a matter of rationalisation and mathematical convenience. $4\pi$ corresponds to the whole solid angle, which usually simplifies when you deal with Gauss' theorem. In other words, you can simply redefine a constant $k$ to be any multiple of another constant, $1/E_0$ in this case.
