Now for the check if it's divisble by 10 it doesn't matter if you add another extra 10 to the total, so I had the same calculation as Eric, (-9 * ($A>4)) but replaced that (also today) for the calculation above.
I KNEW there had to be a better way to do that...I like this one! I was pumped when I thought 2*$a mod 9 would work for all numbers...of course it failed for 9
