Applying If statement to wide range of cells

hi,

I was wondering if there is any way to apply an IF statement, such as If(a4<d38,"0",X); whereas X= what is already contained in the cell, to a large array of cells, say d40:AY900, that already contain somewhat complicated formulas//data, such that you can apply a conditional that would override anything else that is there, without having to go into each individual cell (since there are so many, all of which contain important data//formulas which would be relevant if this one case is not met) and individually typing the conditional in front of the pre-existing formulas....

That's a pretty cryptic question.

im sorry, let me try to elucidate

Say I have a worksheet that is quite large and has 40 columns X 400 rows of cells which contain a series of equations,

Now say after completing the construction of such I realize i want to place a conditional IF statement in front of each equation in each cell, so that the IF statement is the same for all 16,000 cells, and each unique pre-existing equation isn't changed, it is just modified by the IF statement.

Is there any way to simultaneousy put the conditional ( which would be the same for all 16,000) in front of the preexisting (unique) equations which already exist in all 16,000 cells?

Thanks!

.... is this a case for macro??? I have never used macro before so if anyone has a reccomendation for a good intro that would be great if you think that is what i would need to rectify this issue. Thanks!