Recursion is a problem solving technique that involves two ingredients.

1. We need to describe how the problem is when the input is very small (as small as possible), this is known as the base case.

2. The recursive step: incorporate computations involving smaller data to construct your solution.

Practice Exercise: Write a Java recursive method that given a positive integer n calculates:

1^2 + 2^2 + 3^2 +...+ n^2

Note: Can somebody help me with this exercise. It is for intro to computer science. Your help is appreciated.