To do this to any formula you just need to put quote marks around
all the parts of your formula which are not cell references and to
use the cell references for the rest. If you want the "=" to be there
too then you need to include it in the formula.
Taking your new example
=(( C4-C20)*(D4-C21)+(C5-C20)*(D5-C21))/(15-1)
just add a " at the beginning and end of the formula then,
before and after each cell reference add the three characters
" & " and you will get results which look like the formula
you have with numbers instead of cell references.
= " =((" & " C4" & " -" & " C20" & " )*(" & " D4" & " -" & " C21" & " )+(" & " C5" & " -" & " C20" & " )*(" & " D5" & " -" & " C21"
& " ))/(15-1)"
that should do that new formula.
The thing is, why do you want to do this as I seems a weird
thing to do.
Steve.