I am fairly proficient in Excel, but can't seem to figure this one out:

How do I conditionally format a cell to highlight items that are not in correct quantities? For example, I can only order a product in multiples of 10. What if my coworkers place orders for: 10, 30, 50, 75, 90, and 102. I want it to automatically highlight the 75 and 102. It seems like it would be as simple as setting the cell value to "not equal to" 10*x (x=any number). But this doesn't work, how can I do this?

For the record, the quantities are actually more like 20,000 and 10,000...

If not conditional formatting, it would be just as good (perhaps better) if I could use data validation.

Thanks!!