To convert a time into hours, multiply by 24. So you want something like:
(b1-a1)*24
Format as general

Regards
Fred

"Pepino" wrote in message
...
Hello,

I am trying to create a time lookup sheet where at the cross point of
Start
and End time the result is shown in 100 of an hour. So Row 1 has the start
time begining at 8.00 am in 15 minutes increments and Colum A has the End
time begining also in 15 minutes increments 8.00 am 8.15 am and so on. Now
if
you look for example at End time 10.30 am and go accros and look for Start
time 8.00 am at that cross point the result should say 2.5 (two and a half
hours). I do not know what forumla to write for that. Please help.