i need to make this work =sum(c4*d4), but i have some cells that does not
contain anything and the result looks like that #VALUE!

1 c d e(sum)
2
3 3 5 15
4 2 #VALUE!


I don't want anything to apear in e4, or in the worst case i want 0 to apear
in this cell.
Anyone can help me? Thanks