\(R=mN=\frac{\lambda_{av}}{\Delta \lambda}=\frac{(\frac{589.592+588.995}{2})}{(589.592-588.995)}=\frac{589.7935}{0.597}=988\)

\(N=\frac{R}{m}\)

\(m=1\), \(N=988\)

\(m=2\), \(N=494\)