Fill Series only changing one input

[Wildtickamite]

I am not sure if this is possible, but I am hoping that it is. Right now, I
am trying to create a formula (and fill down the column) that calculates the
percentage of a total. My formula right now is as follows:
=C2/(SUM('2010 Consultation'!B12+'2010_Raw Pivot'!C:C))

Column C in the sheet titled (2010_Raw Pivot) contains revenue. I need to
know the percentage of revenue out of the total. However, the total is not
just the summation of all of Column C. I need to take into account a cell
that I have in another sheet (2010 Consultation! - Cell B12).

When I use the fill down command, it changes both C2 and B12, so the next
line looks like this:
=C3/(SUM('2010 Consultation'!B13+'2010_Raw Pivot'!C:C))

How can I keep the B12 constant and always refer to that cell, but change C3
as it goes down the column?

 

[Don Guillett]

$B$12

 

[Fred Smith]

Look up absolute addresses in Help. Essentially, you want $B$12, rather than
B12.

Regards,
Fred