There are two options that you could use. If the answer to your formulas are zero NUMBERS and you want to suppress display of ALL zero numbers then go to Tools|Options and remove the tick from the box marked "Zero values".
If, however, you want to suppress zero (or any other value you choose) result from a formula then do this. Assuming the calculation is to take the contents of A7 and multiply it by the contents of A8 (I don't know what your formula is so you will have to substitute yours for my example) the most simple formula would be =A7*A8 To suppress the zero result use the IF function following the convention IF([condition],[do this if true],[do this if false]). So, in my example =IF(A7*A8=0,"",A7*A8) will return the result of multiplying A7 and A8 if the answer to that sum in non-zero, if it is zero then the formula returns a null string and nothing is seen.
Beware, Excel does not show the text string for the number zero (or any other number) differently from the actual number, although the values in the cell are quite different.