Formula to subtract from last instance of variable in rows above

[Bezurk]

Please can someone help.
Please see screenshot here: Screenshot
There is a column where the user will select the CUSTOMER NAME from a drop-down menu, this will then automatically display the amount of skips that the customer has taken in the TOTAL SKIPS column.
The user will then input how many skips they would like to invoice by putting in the value in the column SKIPS TO INV, the last column OUTSTANDING, is basically the TOTAL SKIP minus SKIPS to INV (to give a total of how many skips are left to invoice).
The issue is that customers are not selected sequentially, thus I need a formula in the TOTAL SKIPS column that will display the last value from the OUTSTANDING column of the last instance of the customer name above.
E.g. When selecting customer name 1, the value displayed in column TOTAL SKIP will show the last value from the OUTSTANDING column of customer 1 which was 3 rows above.

 

[CA_Punit]

What would you like to display in case of Invoice No INA2009002 Customer No 4 (Row 2)
which doesn't have any outstanding above.

If we put a formula in Total SKIP then you cannot enter data automatically.

his will then automatically display the amount of skips that the customer has taken in the TOTAL SKIPS column.

We need to alter that too also.

 

[Bezurk]

Hi there, that’s no problem we can add another column then ?

 

[CA_Punit]

How about this

Book1
	B	C	D	E	F	G	H	I
4	INVOICE	CUSTOMER NAME	SITE ADDRESS	ORDER NO	TOTAL SKIP	SKIPS TO INV	OUTSTANDING	Total Skip (Helper)
5	INA2009002	1	j	4567	3	1	10
6	INA2009002	4	b	7345	2	3	4	10
7	INA2009002	1	j	4567				4
8	INA2009004	11
9	INA2009005	1
10	INA2009006	1	j	4567
11	INA2009007	1
12	INA2009008	4
13	INA2009009	4
Sheet2

Cell Formulas
Range	Formula
I5:I7	I5	=IFERROR(IF(MATCH(B5,$B$4:B4,0),LOOKUP(2,--($B$4:B4=B5),$H$4:H4)),"")

 

[CA_Punit]

Sorry i didnt check for formula. Please replace the formula with
=IFERROR(IF(MATCH(B5,$B$4:B4,0),LOOKUP(9999999999999,ROW($H$4:H4)/($B$4:B4=B5),$H$4:H4)),"")

 

[Bezurk]

Thank you kindly, I’m back at the office tomorrow and will give it a try.