I keep track of my employee's vacations on a spreadsheet. At times, I need to update various days where the office is closed. These can be statuatory holidays or company days. Some days the employees vacation allotment is not decremented. These I need to shade the cell with a colour. There are days where the office is closed and all employees need to take a vacation day. In these cells, I would put in a 1 to decrement the vacation days by one. Below is just a part of the spreadsheet. How can this be done rather than manually for each individual employee?