There is a one-column table. A user would type a four-digit number into a cell. The cell would automatically convert it to a stored format with that number.

For example: Cell A2 is blank
I type 45 and press enter.
Excel automatically converts the cell to read RM17-0045.

If another user types 102 into cell A3
Excel automatically converts the cell to read RM17-0102.

This would be for all entries in column A.

Could anyone show me how to do this? I want to learn.
Thanks!