I think you'll find Bernard, that the restriction for array formulas *and*
Sumproduct apply *only* to ROWS in the earlier versions.
XL handled the 256 columns without a hitch.
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Regards,
RD
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Please keep all correspondence within the Group, so all may benefit !
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But full column/row reference such as A:A or 1:1 are permit in SUMPRODUCT
only in Excel 2007 and 2010. In earlier versions you would need ranges
=SUMPRODUCT(--(MOD(COLUMN(A1:Z1),2)=0),A1:Z1)
best wishes