converting to decimal time

[John Habermann <john test wilderness org au>]

Hi

I am just trying to use gnumeric to calculate the amount of money earned based on the number of hours worked 
and can't figure out if it is possible to convert something in 'hour:minute' format to decimal so that I can 
multiple it by an hourly rate. I have looked at all the  functions in date&time but none seems to do that 
although I may well not be underseperate the hours and minutes into separate columns. Thanks for any help and 
sorry if this is a really dumb question, never really gone into much depth in spreadsheets before.

cheers
John Habermann