Turning a set amount of hours into days

Bad thread title but I really couldn't think of a better one/how to explain it!

Basically, I am trying to create a spreadsheet that records the shifts that people work and to calculate sickness, overtime etc. I am recording each shift in hours (7.5 per shift). However, the person asking for the spreadsheet needs annual leave recorded in days.

How can I make excel know that 7.5 hours = 1 day?

why can't you take the hours and divide by 7.5 and round it off.
what happens to partial days? if the hours are say 17, you would get 2.67 days.
If it's not that simple, attach a sample to show what results you are expecting.
modytrane