An IF formula is the standard way to do it. Your condition could be
simplified from N(D24)=0 to D24=0 unless the issue is that it might
contain text. If it is possible for D24 to contain an error that you
want to ignore, or it you also need to check C48, you might want to consider
COUNT(D24,C48)<2
as your condition.

If all zero values are to be ignored, another possibility would be
Tools|Options|View and uncheck "Zero values"

Jerry

Ted wrote:

I was trying to get it to ignore empty cells and leave the cell where the sum
would normally display blank (as in without a zero)

I've used this now:

=IF(N(D24)=0,"",ROUND(D24*C48,3))

thanks for your help though, Ted.