Fun with RNGs: Calculating π
So, calculating π is a fun pastime for people it seems. There are many ways to do it, but this one is mine. It’s 12 lines of code, it wastes a lot of electricity and it takes forever to converge.
1 

What’s going on here? First we initialize our random number generator. Then for 1 to the number of trials we specify in the argument we do the following:
 Generate two random numbers between 0 and 1. We use one for the X coordinate and one for the Y coordinate of a point.
 We test if the point (X,Y) is inside the unit circle by using the formula for a circle (x^2 + y^2 = r^2).
 If the point (X,Y) is inside the circle we return a 1 otherwise a zero.
Then we take the average of all those zeros and ones and multiply it by a magic number, 4. We have to multiply by four because the points we generate are all in the upper right quadrant of the xyplane.
How bad is it? Here’s some output:
Number Of Trials  Estimate of Pi 

10  3.6 
100  3.24 
1000  3.156 
10000  3.1856 
100000  3.14064 
1000000  3.139544 
10000000  3.1426372 
100000000  3.14183268 
1000000000  3.141593 (Took 2:23 to complete) 