Numbering Create Automatically

PO Number Qty In PO Total Quantity In PO I Need Numbering Like This
1111 1 1 1/1/1
2222 2 4 1/2/4
2222 2 4 3/4/4
3333 3 3 1/3/3
4444 4 4 1/4/4
5555 5 31 1/5/31
5555 5 31 6/10/31
5555 6 31 11/16/31
5555 7 31 17/23/31
5555 8 31 24/31/31
6666 10 10 1/10/11
6666 1 1 11/11/11