如果范围中的工作日与特定单元格相匹配，如何使用总和（如果要添加值）

Question

I have an excel document that has 101 worksheets. 100 of the worksheets contain data for a particular month ie one of the worksheets is called 'May 2010', followed by a worksheet called 'June 2010'. On each of these sheets there is a list of dates in column A, and a list of revenue $s in column B.

I'm creating a summary sheet that is going to use the indirect function to look at all the different sheets and basically sum all of the revenue made on each day of the week in each month. For example I want to sum all the revenue made on Tuesdays in October of 2014.

I was trying to use an array function like so:

=SUM((--WEEKDAY(('May 2010'!A2:A22)=2)*(('May 2010'!B2:B22))))

I found this online. I am trying to see if i can sum all of the revenue values in column B on the sheet entitled 'May 2010' if the corresponding value in column A is a Monday. The values in column A are of the form '11-May'

I think my problem is that i'm trying to check the weekday of a range of values but I'm not really sure. I don't fully understand how array functions work or even if i'm supposed to be using them. I open to any suggestions as long as it doesn't require me to go through each of my 100 sheets manually and create a column that contains the weekdays of the corresponding dates. Any thoughts?

Answer 1

The short answer is that the brackets aren't quite right.

=SUM(((WEEKDAY('May 2010'!A2:A22)=2)*('May 2010'!B2:B22)))

or

=SUMPRODUCT(((WEEKDAY('May 2010'!A2:A22)=2)*('May 2010'!B2:B22)))

if you prefer not to have to enter it as an array formula.

If as @XOR LX suggests you actually want to repeat this over all of your sheets, it is a bit more tricky.