Why z = 5?

Question

https://code.sololearn.com/c82lWlSeqV31/?ref=app

Answer 1

when z is 2
z = z * z //z = 4
z++ //z = 5

Answer 2

1st loop:
x = 1 * 1
x++ //x == 2

2nd loop:
x = 2 * 2
x++ //x == 5

loop end.

Answer 3

Thanks!