How do I format a cell to display decimal hours?

Instead of displaying 3:45 (for 3 hours, 45 minutes), which is one of
the standard formats, I'd like to display 3.75 (hours). h.hh doesn't
do it.

The above is formatting for an elapsed time calculation (finish time
minus start time). (On a "time card")

Excel 2000. Will a later Excel do it for me?

Some good source for a parsing function?

Any good reference?

Thanks,

Fred Holmes