I don't know why this output is 2? Could you guys help?

Question

public class Main {
public static void main(String[] args) {
int[]a={100,89,6,3};
for(int i=1;i<a.length;i++){
a[i]=a[i-1]%a[i];
}

System.out.println(a[3]);

}
}

Answer 1

You can put the code on sololearn playground and print out the values for each iteration of the loop so it is easier to understand what happens:
https://code.sololearn.com/ceTVhn1FLgBm/?ref=app

Answer 2

Killiam Chances See the formula and notice that the value at each index [i] depends on the value at the index before it [i-1]. Start with determining what is in a[1] and work forward until you reach i=3.

When i=1:
a[1] = a[1-1]%a[1]
= a[0]%a[1]
= 100%89
= 11
Now find what is in a[2].
a[2] = a[2-1]%a[2]
= a[1]%a[2]
= 11%6
= 5
Finally, see what gets filled in at a[3].
a[3] = a[3-1]%a[3]
= a[2]%a[3]
= 5%3
= 2