I need your help to do an operation. I have a worksheet that I calculate with f9 key.L18 cell is "OK" or "CHANGE" depending on 20 cells. ( for example : A20 , A25 , B40 , B45........ ) when all 20 of these cells = 1, the L18 cell becomes "OK" and the calculation must stop. I press f9 once for each calculation until the L18 cell is "OK". Once I press the f9 key, the calculation starts and the calculation is done when the L18 cell is "ok". I can not speak English enough. I hope I can tell you my problem. and I hope I did not disrespect. Thank you in advance for your help.