Date/Time format problem

I am trying to use a summed subtotal hours value (in the [hh]:mm format) in a formula multiplying it with my $/hr value (in the currency format). eg. 47:40*$25.00 but end up with $49.65 (clearly wrong). It is actually because the true value is 1.986111111*$25.00. So how do I convert the value into seperate hour and minute values in a decimal format? Thus far the hour() and minute() formulae don't seem to work, so where to now...
Anyone out there...
Thanx
R2