Adding in Excel

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Guest

I have a time sheet. One row has the total number of Regular hours worked in
7 days. The next row has the total number of Overtime hours worked in those 7
days, the next row regular hours, the next overtime hours, and so on for 5
rows down. At the bottom of the sheet I need to add only the Regular hours in
one cell and I need the total Overtime hours in another cell. So I need a
formula that will add every other row, or every other number in the same
column.
 
The easiest method would be

=A1+A3+A5+A7+A9
=A2+A4+A6+A8+A10

You can also use something like

=SUMPRODUCT(MOD(ROW(A1:A10),2),A1:A10)
=SUMPRODUCT(1-MOD(ROW(A1:A10),2,A1:A10)

This way you can just change the range values if you want to expand the
range without specifying the specific cells.
 
Hi Sloth. If it's not too much trouble, would you mind explaining how that
formula works. I'm afraid I'm struggling with the mod and sumproduct
functions. Thanks in advance.
 
SUMPRODUCT multiplies values from two arrays
MOD take the remainder of the division
ROW give the row of the cell

Broken Down...
ROW(A1:A10) -> {1,2,3,4,5,6,7,8,9,10} *NOTE:{} signifies an array
MOD(ROW(A1:A10),2) -> {1,0,1,0,1,0,1,0,1,0}
SUMPRODUCT(~~~) -> {1,0,1,0,1,0,1,0,1,0}*{A1,A2,A3,A4,A5,A6,A7,A8,A9,A10}
this becomes...
1*A1+0*A2+1*A3+0*A4+...

the second formula uses 1- and becomes
0*A1+1*A2+0*A3+1*A4+...

Hope this helps
 
Thank you very much Sloth. That helps alot. I'm going to have to experiment
with it to fully capture the concept. Thanks again.
 
Another option.

Insert a helper column (say column A).
Put R, OT, R, OT, R, OT, ... down that column.

Then you can use a formula like:

=sumproduct(--(a1:a20="R"),(b1:b20))

Adjust the ranges to match--but you can't use whole columns.

=sumproduct() likes to work with numbers. The -- stuff changes trues and falses
to 1's and 0's.

Bob Phillips explains =sumproduct() in much more detail here:
http://www.xldynamic.com/source/xld.SUMPRODUCT.html

And J.E. McGimpsey has some notes at:
http://mcgimpsey.com/excel/formulae/doubleneg.html

What's nice about this formula is that if you insert a row, you don't break the
formula. (When you add those Vacation hours and Sick hours and ....)
 
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