Recursion can seem rather odd at first. This video explains how recursive functions work by showing you how your calculator finds a square root by using the Newton-Raphson method.
The code used in this video is available at:-
https://lyw4.life/Resources/python.php
and scrolling down to topic 58. There is also the code for another program which calculates the n'th root for those who are a little more adventurous.