Just adding to what Jeff said (which is all 100% correct)…
- Your “mo” column is redundant. You could simply just use +1 in your math formula.
- Because the next ticket number is based on the current number of rows, if you ever delete any rows then things will get messed up. So that’s another thing to be careful of.
Have a read through the below thread for more discussion on this topic, and a couple more possible solutions.
Like I said, there are a number of different ways to approach this, and several different potential solutions. None of them is perfect, and there is no one size fits all. It just depends on the specific use case.