I am looking for something that will find the last cell of
data in a column, here is what I want to do

the function I have is

=if(a1=0,0,(b1-$cS10)*d1)

C10 is the total for that column

now that works fine on sheet 1 but on sheet 2 and then
sheet the total is in cell C23, due to the nature of the
spreadsheets I am coding it so the formulas get entered
each time by clicking a button. How do I find the last
cell containing data in column C and then use it in the
formula. Once I can find it on one sheet then I can find
it on the rest

Thanks