Which of the following is not correct ?
1
2104360587 is divisible by 9.
2
15128751 is not divisible by 9.
3
All possible values of digit z in the number 31z5 so that this number is a multiple of 3 are 3, 6 and 8.
4
For the number 21y5 to be a multiple of 9, the digit y must be 1.