Why is the output 4, can u explain ?

Question

I'm always mistakening, don't want to remember, want to understand.
If I understand, than I'll remember. Please give a link on these 2 ex. if they're already on sololearn.
Random rand = new Random();
int x = rand.nextInt(5) %10;
System.out.print(x); //Output 4
Thank you!

private static int f(int i) {
if(i<=1)
return 1;
else
return(2+f(i-1)); //Here will be 4! and how 1 adds, from previous return 1 ?
}
public static void main(String[] a){
System.out.print(f(3)); // Outputs 5 ?
}

Answer 1

if we run the f(3) step by step,
f(3) = 2 + f(2) // will go to the else part
f(3) = 2 + 2 + f(1) // again to the else part
f(3) = 2 + 2 + 1 // hit the base condition
f(3) = 5 !!

Im not sure about the first question...
the presence of random there indicates that x does not consistenly output 4. Though it just plays from 0 to 4...