Rolling Formula to Calculate in a specific column

[ahuang3433]

I am trying to create a rolling formula to calculate net inventory levels. Here is an example of what I'm working with. How can I get column D to keep rolling based on the inventory available of a specific part?

Part	Demand	Inventory Available	Net Inventory
A	1000​	5000​	4000​
B	1000​	3000​	2000​
C	1000​	4000​	3000​
C	1000​	4000​	2000​
A	1000​	5000​	3000​
E	1000​	3000​	2000​
F	1000​	2000​	1000​
E	1000​	3000​	1000​
D	1000​	1000​	0​
A	1000​	5000​	2000​
B	1000​	3000​	1000​
A	1000​	5000​	1000​

 

[jasonb75]

Assuming "Part" is in A1, try this in D2 and fill down

=C2-SUMIF(A$2:A2,A2,B$2:B2)

From your example it clear how you enter deductions from your inventory but not how you enter increases when new stock arrives.

 

[ahuang3433]

It worked perfectly. Thanks!