I need help guys to understanding function

[Alzahrani]

could you please get help to understand to write program has two function . i found it hard and i am look to get easy to follow it .

for example to calculate approximate Pi by getting from user number of rectangle.

[Chervil]

Function help here: http://www.cplusplus.com/doc/tutorial/functions/

calculate approximate Pi

there are many ways to calculate pi. Which algorithm are you using?