Time in digital (for large numbers)

Hello ... my first post here.  :)

As a freelancer, I use Excel to track the hours I work on a particular job.  I then convert the total time worked (say 2:45 which is formatted as h:mm) into decimal so I can multiply it by my hourly rate.  I use the formula "=(A1-INT(A1))*24", so for 2:45 I'd get 2.8.

All good so far.  But for a job of many days, let's say I worked a total time of 69hrs 55min.  For reasons I don't quite understand, I need to change the cell format slightly to 'elapsed' time ([h]:mm) to get 69:55 to appear.

But when I go to convert these larger numbers into digital, it won't work.  The formula mentioned above gives me a crazy result (526:00:00).  I found some other suggestions online, but none worked.  It seems that using elapsed time is throwing a spanner in the works.

Anyone have a suggestion?

Many thanks!