I have a request to program one cell of a spreadsheet that
the user can type a minute value (i.e. 00:10:00) and when
they press the enter key (with focus on this cell) a timer
starts and the display changes to count down to 00:00:00.
The value will be entered in minutes, so if there is any
way that the user just has to enter "10" instead of the
entire 8 character time format, that would be ideal.

Can anyone help with this?