Here's a clever way to find $\pi$ (see Cheney, et. al, 5th ed., p. 39). See if you can translate this "pseudo-code" into a working program to find $\pi$. It'll allow you to practice with for-loops and programming formulas into the computer.

$a\leftarrow\sqrt{2}$
$b\leftarrow 0$
$x\leftarrow 2+\sqrt{2}$
for k=1 to 5 (or more)
$t\leftarrow \sqrt{a}$
$b\leftarrow t(1+b)/(a+b)$
$a\leftarrow \frac{1}{2}(t+1/t)$
$x\leftarrow xb(1+a)/(1+b)$
output x
end-for