Avoiding the error
Two other thoughts: you seem to be adding together data in a row. If you use the sum() function, you will get no error. Because you will get an error if you changed the multiply to a divide and all the values are blank, I'd recommend this general purpose solution:
=if(sum(d26:h26)=0,"",sum(d26:h26)*i26)
This says: if the sum of all the fields is 0 (they are all blank or zero), leave the cell blank, otherwise, multiply the sum of the cells by i26. To consider: if zero is a valid response different from blank, this needs to be done differently (this is the case for some statistical functions).