Current Electricity

In an experiment to determine the figure of merit of a galvanometer by half deflection method, a student constructed the following circuit.

He unplugged a resistance of $5200 \Omega$ in R . When $\mathrm{K}_1$ is closed and $\mathrm{K}_2$ is open, the deflection observed in the galvanometer is 26 div. When $K_2$ is also closed and a resistance of $90 \Omega$ is removed in S , the deflection between 13 div. The resistance of galvanometer is nearly