Getting a 0 value when formula multiplies 2 cells but 1 is empty

Hello everybody, just signed up since i cant get it figured out myself.
Question itself will show i am not really great with excel.



I am using this in C10 to C18
=ABS(A10-B10)
To get the difference between A10:A18 and B10:B18.
However A16 is 58009 and B16 is blank but C16 is still showing 58009 while it has to be 0.
Makes sense with the formula used.

What is a better formula i can use to calculate this?

Thanks