Excel Locked Cell Query

I want to allow the user to increase and decrease the decimal places of a locked cell in ex开发者_运维知识库cel 2007 without allowing other formatting options. Can anyone tell me how to do this?

Add a control such as a spinner or two buttons to the worksheet. One will add zeros, the other will remove zeros. Have a cell that stores the number of zeros. When they click the button either subtract or add to the cell value, have a low and high number of zeros. Then use the format combined with the string function to set the number of zeros in the locked cell.