Sum Columns by set of 4 weeks

[MiguelS]

I have this data, and I want to sum Row 5, which is Row#04 in monthly buckets. WK1-WK4 in MOnth 1, wk5-wk8 in Month 2....

The Weeks go up to Wk 26, but there is 15k rows in the spreadsheet.

Can someone help me with this. The WK1, WK2, ...wont change, but the dates do.

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	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V	W	X
1	Row#	RowDescription	Material	INV	SS	INV-SS	Past	WK1 02/12	WK2 02/19	WK3 02/26	WK4 03/05	WK5 03/12	WK6 03/19	WK7 03/26	WK8 04/02	WK9 04/09	WK10 04/16	WK11 04/23	WK12 04/30	WK13 05/07	WK14 05/14	WK15 05/21	WK16 05/28	WK17 06/04
2	01	Open PO By Due Date	03-042616-01	0	0	0	0	0	0	0	0	0	0	0	10	0	0	0	0	0	0	0	0	0
3	02	Demands By Need Date	03-042616-01	0	4	0	0	0	0	0	2	0	1	0	1	0	1	0	1	0	1	0	1	1
4	03	Ending Bal=INV + PO - SS - Dmd	03-042616-01	5	0	1	0	1	1	1	-1	-1	-2	-2	7	7	6	6	5	5	4	4	3	2
5	04	Fcstd Reqs By Need Date	03-042616-01	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
6	05	NONCONS,LT=42	03-042616-01	5	4	1	0
7	01	Open PO By Due Date	03-042741-00	0	0	0	0	0	1	2	0	0	0	0	0	0	0	0	0	0	0	0	0	0
8	02	Demands By Need Date	03-042741-00	0	3	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
9	03	Ending Bal=INV + PO - SS - Dmd	03-042741-00	1	0	-2	0	-2	-1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
10	04	Fcstd Reqs By Need Date	03-042741-00	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
11	05	NONCONS,LT=42	03-042741-00	1	3	-2	0
12	01	Open PO By Due Date	03-045549-00	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0
13	02	Demands By Need Date	03-045549-00	0	6	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
14	03	Ending Bal=INV + PO - SS - Dmd	03-045549-00	3	0	-3	0	-3	-3	-3	-3	-3	-3	-2	-2	-2	-2	-2	-2	-2	-2	-2	-2	-2
15	04	Fcstd Reqs By Need Date	03-045549-00	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
16	05	NONCONS,LT=42	03-045549-00	3	6	-3	0
17	01	Open PO By Due Date	03-045549-01	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0	0
18	02	Demands By Need Date	03-045549-01	0	7	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
19	03	Ending Bal=INV + PO - SS - Dmd	03-045549-01	4	0	-3	0	-3	-3	-3	-3	-3	-2	-2	-2	-2	-2	-2	-2	-2	-2	-2	-2	-2
20	04	Fcstd Reqs By Need Date	03-045549-01	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
21	05	NONCONS,LT=42	03-045549-01	4	7	-3	0
22	01	Open PO By Due Date	03-052673-09	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
23	02	Demands By Need Date	03-052673-09	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	1	0	0	0	0	0
24	03	Ending Bal=INV + PO - SS - Dmd	03-052673-09	1	0	1	0	1	1	0	0	0	0	0	0	0	0	0	-1	-1	-1	-1	-1	-1
25	04	Fcstd Reqs By Need Date	03-052673-09	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0	0
26	05	NONCONS,LT=42	03-052673-09	1	0	1	0
27	01	Open PO By Due Date	03-055640-01	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
28	02	Demands By Need Date	03-055640-01	0	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0
29	03	Ending Bal=INV + PO - SS - Dmd	03-055640-01	0	0	0	0	0	0	0	0	0	0	0	-1	-1	-1	-1	-1	-1	-1	-1	-1	-1
30	04	Fcstd Reqs By Need Date	03-055640-01	0	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0
31	05	NONCONS,LT=42	03-055640-01	0	0	0	0
32	01	Open PO By Due Date	03-056962-02	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
33	02	Demands By Need Date	03-056962-02	0	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
34	03	Ending Bal=INV + PO - SS - Dmd	03-056962-02	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
35	04	Fcstd Reqs By Need Date	03-056962-02	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
36	05	NONCONS,LT=42	03-056962-02	1	1	0	0
37	01	Open PO By Due Date	03-101192-02	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
38	02	Demands By Need Date	03-101192-02	0	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
39	03	Ending Bal=INV + PO - SS - Dmd	03-101192-02	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
40	04	Fcstd Reqs By Need Date	03-101192-02	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
41	05	NONCONS,LT=42	03-101192-02	1	1	0	0
42	01	Open PO By Due Date	03-10193-01	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
43	02	Demands By Need Date	03-10193-01	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	2	2	0	0	0	0
44	03	Ending Bal=INV + PO - SS - Dmd	03-10193-01	3	0	3	0	3	3	3	3	3	3	3	3	3	3	3	1	-1	-1	-1	-1	-1
45	04	Fcstd Reqs By Need Date	03-10193-01	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	3	0	0	0	0

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Forecast1​