Exer. $65-66:$ Some calculators use an algorithm similar to the following to approximate $\sqrt{N}$ for a positive real number $N:$ Let $x_{1}=N / 2$ and find successive approximations $x_{2}, x_{3}, \ldots$ by using
$$
x_{2}=\frac{1}{2}\left(x_{1}+\frac{N}{x_{1}}\right), \quad x_{3}=\frac{1}{2}\left(x_{2}+\frac{N}{x_{2}}\right), \quad \dots
$$
until the desired accuracy is obtained. Use this method to approximate the radical to six-decimal-place accuracy.
$$\sqrt{5}$$