This should be the simplest example of conditional formatting but I can't figure it out. I havave two columns seperated by several dozen other columns ('C'-original data, 'BO'- calculated value) and I need to highlight the calculated value if it is not equal to the original value. I can do this on a cell by cell basis but can't see how to apply it to a whole column withoug adding a rule for every row (there are many 1000s of rows).

What am I missing?