Adding every other cell in a column with =SUM(MOD-

 

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Jenny asks "Is there a quick way of adding every other cell ?, I have a column of about 250 cells, and I have to select them manually using Ctrl. Can you help ?"

Jenny, this is a matter of using a little math to remember how to determine if a number is even or is odd, and then translate that into the formula.

The formula
=MOD(A1,2)
would return 0 if the number is even and 1 if odd. If we use instead of A1, the ROW() function, we can know if a particular row is even or odd. Now, suppose you're trying to calculate this formula

=A1+A3+A5+A7+A9 ... etc.
or this one
=SUM(A1,A3,A5,A7...)

=SUM((MOD(ROW(A1:A250)-ROW(A1),2)=0)*(A1:A250))

Remember, this is a CSE Formula, to enter it you must press at the same time Control Shift Enter, instead of just Enter as regular formulas.

You can also use this non-array formula

=SUMPRODUCT((MOD(ROW(A1:A250)-ROW(A1),2)=0)*(A1:A250))

By Juan Pablo Gonzalez on 24-Jan-2002
MrExcel.com Consulting can be hired to implement this concept, or many other cool applications, with your data.

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