java recursion- please explain each step involved

// sample recursion methods public class recursionDemo3 { // Evaluate each method below: public int mysl(int nn) { if(n-0) return 1; else return 2 + mysl(nn - 1); } public int mys2(int nn) { if(n=1) return 1; else if(n=2) return 1: else return mys2(nn - 2) + mys2nn-1); > public int mys3(int nn) 4 if(n==0) return 0; else return nn % 10 + mys3(nn/10); 1 public int mys4(int nn) if(n==0) return 0; else return I + mys4nn/10): } public int mys(int n, int k) if(k=0) return 1 : else return mys5(n, k-1); > public void mys6 int nn) if(nn !-0) mys6 nn 2): System.out.println(nn nn + "")