Hi,
Your cumulative quantity and same way cumulative values calculated
First transaction quantity = 15 Cumulative quantity = 15
Second transaction = 10 Cumulative quantity = 25 (15+10)
Third transaction = -1 Cumulative quantity = 24 (25-1)
Fourth transaction = 1 Cumulative quantity = 25 (24 +1)
Fifth transaction = -1 Cumulative quantity = 24 (25 -1)
Last transaction = -1 Cumulative quantity = 23 (24 -1)
The final cumulative quantity is 23. In short, cumulative quantity is calculated from previous values based on transaction its get added or subtracted.
Thanks & Regards,
Nagarajan