Moment of momentum is r×P $\begin{aligned}
& \overrightarrow{\mathrm{L}}=\overrightarrow{\mathrm{r}} \times \mathrm{m} \overrightarrow{\mathrm{v}} \
& \mathrm{L}=\mathrm{mvr}=\frac{\mathrm{nh}}{2 \pi}=\frac{4 \mathrm{h}}{2 \pi}=\frac{2 \mathrm{h}}{\pi}
\end{aligned}$