Hi muggers

I have a quick query regarding time in excel.

Without thinking in a previous life, I have coded all the times of sightings etc as straight numeric in excel and had some notion of being able to convert to a time field later. I have tried reformatting the cells, but that converts all numbers to zero. Arrrrrrhhh.

Im wanting to calculate a time difference between start and end times. Simple?

Can someone with real excel experience give me some help?

regards

chris