I don’t know how to solve this. But, i=\frac{2\pi a_0 e}{v} is used to calculate that. I have seen another equation, i= \frac{ev}{2\pi a_0}. I don’t know which one is correct. But, if you input MKS values in the second equation except for a_0 for some reason, and then you input 100a_0 (in CGS) instead of a_0 it gets accepted by Gonitzoggo. I think there is a problem in H in Parallel Universe | গণিতযজ্ঞ. Maybe the answer setter made a mistake while measuring Bohr radius, maybe he made a mistake of not dividing a_0 (CGS value) by 100 and multiplied by 100 instead ( I think & there’s a huge chance that I am wrong). Experts!! Help us a little!! @math_rocker @barnalidas1974at @abrar_fahim01 @Mesbatur_Rahman_Niloy @adnansgphs @ratulpaul @ROHAN1230 @shahriaraminarif1234 & @ all the experts whom I didn’t mention 
first, from de-Broglie equation, determine the value of 2 \pi r. As the e^- takes t times to complete 1 full revolution, then the value of 2 \pi r will be equal to vt. Now, as we are searching for the current due to the revolution, we can use I= \frac {Q}{t} instead and we are done.
so, I=\frac{ev_n^2m_e}{nh} can be used for general cases right?