Convert data into standard military time format

[geog]

I am trying to convert military time data into an Excel recognized time
format so that I can perfrom time calculations (add/subtract hours).

My main problem is that the data is not all stored in a 4 digit format. Some
is stored as "300" instead of "0300". I have tried formatting the cells to
hhmm, but I end up with a cell containing "0000" regardless of the data that
was there prior. I also tried the following:
=text(cell, "0000")
That displays the data correctly, but I can not perform any time
calculations on it.

Does anyone know how I can convert my existing data into a standard military
time format? Any help would be greatly appreciated.

Does anyone know how I can get my data in

 

[Dave Peterson]

=--(TEXT(A1,"00\:00"))

format the cell as time:
hh:mm:ss
????

 

[geog]

thanks - that worked for formatting the time. I really appreciate the help.