I want to be able to enter NA in a cell and then later use this cell in a formula. So, I think I would like NA to be a number format of 0. If I just enter NA, Excel considers it text and I get an error when I use the cell in a formula. I do this so I can copy the formulas down. Sometimes there is a value in the cell and sometimes it isn't applicable (the person in a payroll spreadsheet isn't eligible for certain hours like sick)I use NA so that I know not to imput anything in that cell for that person as he/she is not eligible. However they might be eligible in the future, and if they are, all I would have to do is put in the proper value and the proper calculation would pop out. I know I can protect or lock the cells, but I'd rather have the visual NA reminder.