Stock Control, SUM IF

Ok got the first bit done.
Next bit is more complicated.
My range is from col C to AK. Rows 5 to 55

Rows 16, 18, 20, 22 etc Contain quantities
Rows 13, 24, 35 etc contain item name

I have set it so that when there is a number in C18 it shows yellow.
I would like to set it so that if there is a number in C18, C20, C22 then C24 also shows yellow.
I have done it with conditional formatting, Formula is, =C18:C22>0, but I dont want to repeat this hundreds of times for each row and col.

How do I do this?