If the series limit wavelength of Lyman series for the hydrogen...

\frac{1}{\lambda}=R$\left[\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right]$ For limiting wavelength of Lyman series $$n_{1}=1, n_{2}=\infty \quad \frac{1}{\lambda_{L}}=R$$ For limiting wavelength of Balmer series $n_{1}=2, n_{2}=\infty$ \begin{array}{l} \frac{1}{\lambda_{B}}=R\left(\frac{1}{4}\right) \Rightarrow \lambda_{B}=\frac{4}{R} \\ \therefore \lambda_{B}=4 \lambda_{L}=4 \times 912 \AA \end{array}