How long should you make a simple pendulum so its period is 200. ms?

So we want to know how long should we make the simple pendulum so it's period is T=200 ms = 0.2 s. Since the formula for simple pendulum is T=2*pi*sqrt (L/g) where T is the period, L is the length and g=9.81 m/s^2. Now we need to invert the formula to get the length: T/2pi=sqrt (L/g), we square both sides of the equation: (T/2pi) ^2=L/g and multiply both sides with g:

g * (T/2pi) ^2=L. Now we input the numbers and get that the length L = 0.00995m.