Sum specific monthly columns (i.e. Jan - Oct or Apr - Jun)

I have monthly data which and am looking to extract specific data ranges such as Jan - Oct or Apr - Sept., but I need to be able to instruct the formula as to how many months to total.

i.e. Need sum of Jan - Oct to be 81 for the ID for Atlantic (81) or sum Jan - Apr for same (27)

I have attempted to use sumif and sumproduct but I am obviously missing something, any help would be greatly appreciated.



ID Name Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

A625088188E102F2 Atlantic 7 6 7 7 7 10 4 11 7 7 4 4
D03461E15BCA35A3 Southern 2 4 1 3 2 12 7 4 1 6 8 4
7BBFC8FAEC53948B Florida 8 4 5 2 4 4 5 10 6 4 1
59C69C4C7E1B18FB Bayside 22 10 17 13 7 14 14 10 14 8 11 12
587891C4EC264742 B AND R 1 10 12 13 6 5 1 9 12 15 14 5
AE2394BBB3BE00C0 Better Buns 4 12 6 3 2 5 4 4 4 7 3 4
FE2D38105D96ACF2 COUNTY 18 18 14 12 15 11 11 12 12 21 17 11
16E0C5E041CC9E76 BURNSIDE 5 7 7 7 8 7 3 16 9 9 8 7
C7CE3043C1D0F483 C & C 19 15 21 27 26 35 30 36 35 36 38 31