Formula to skip hidden columns

[Mldeuser]

Hello

I have a sales worksheet that covers 2009-2011. I need a formula that can sum the previous 12 months. The columns are as follows

03/11, 02/11 YTD, 02/11-03/10, 02/11

I need to only sum the columns 03/11, 02/11, 01/11 and so on skipping the two hidden columns between each monthly column.

I hope this makes sense

Thank you

 

[GaryWMn]

Assume your data begins in B2, enter the following formula in A2 as an array. (To enter a formula as an array, type the formula and press Ctrl+Shift+Enter.)

=SUM(IF(MOD(COLUMN(OFFSET(B2,0,0,1,36))-COLUMN(B2),3)=0,OFFSET(B2,0,0,1,36),0))

 

[Mldeuser]

Thank you for the formula but it is not skipping the two hidden columns.

I placed the formula in cell A2 and entered information into cells B2 through E2. The formula should only add cells B2 & E2, however it is adding B2 through E2

Any thoughts

Thank you

 

[GaryWMn]

Just to clarify, did you use Ctrl+Shift+Enter to enter the formula?