A logical expression returns with TRUE or FALSE (Boolean values); put a
number in A1 and try this formula =A15
When you perform an arithmetic operation on a Boolean Value, Excel treats
TRUE as 1 and FALSE as zero
Try =2*(A15)
So to keep just 1 or zero we could multiple by 1: =1*(A15)
Or we could negate the value twice =-(A15) returns with -1 or 0 while
=--(A15) will return either 1 or 0
In short, the double negation is the more efficient way to coerce Boolean
values to numeric values 1/0
For more read these
http://www.xldynamic.com/source/xld.SUMPRODUCT.html
http://mcgimpsey.com/excel/formulae/doubleneg.html
best wishes
--
Bernard V Liengme
www.stfx.ca/people/bliengme
remove caps from email

"WLMPilot" wrote in message
...
I spotted this in a questions and want to know what the dashes are for. I
have also seen dashes used in the SUMPRODUCT function. This is copied &
pasted to show entire question/answer

QUESTION:
=IF(AND(A4="4/12/2006",A4<="9/12/2006"),"49")

This should show next week as 'Week 49' but doesn't. I want to add
another
three IF to this string so that I can get the month sorted out in Week
order?

ANSWER:
Try it as:
=IF(AND(A4=--"4/12/2006",A4<=--"9/12/2006"),49)