I am designing a time sheet and am trying to do some simple math with 'custom' formatted cells.

For example: I have formatted A1 and B1 with the custom format:

00":"00.

Therefore when I type in, say 0600 (for a start time) in A1, and 1430 (for an end time) in B1, the time displayed in those cells is 06:00 and 14:30 respectively. This makes it quick and easy to type in the scheduled hours for an employee.

Now the problem I'm having is doing some math with these cells. What I would like to do is subtract the start time from the end time for the hours worked and place that result in cell C1, as - I guess it would be decimal format - 8.50, rather than 8:30.

I would really appreciate some help, thank you.

Michael