I am sorry. You are right I cannot explain it really well. I can send
you the spreadsheet so that you will have better understanding. I
tried your formula, and it certainly worked. But, it is not what I
want. I dont only want to make all negative numbers in column j 0,
but also, I want a number in the Safety column that makes the
Production column 0. There is no fomula in columns G,H and I. But,
mathematically thinking, in order to make a negative number 0 in
column J, safety = Inv. - Orders, so 45-25=20. As a result, the
production column(J) will be 0 ( 25 + 20 - 45 = 0) So, I first want
to find an appropriate number for safety to make the negative
production number in column J 0. I hope I am clear enough this time.

So I am clear on this... you want to let the user enter a number in the
Safety column and if that number makes the Production calculation negative,
you want the spreadsheet to change it in such a way as to make the
Production value 0... is that correct? If so, then I don't see how you will
do that with a worksheet formula (not unless you can have 2 Safety
columns... one for the "actual" value that the user types in and another for
the "calculated" value that the spreadsheet calculates); rather, it seems
like a macro will be necessary.

Rick