Calculating Time: add additional hours

I need to record minutes then calculate the totals on a daily basis. Using the normal number formats doesn't work, because 60 minutes is shown as 0.60, not 1.00. So, 40 plus 40 is calculated as 80 not 1.20. Using the date/time formats doesnt work either, because the system wants to show the date. Similarly Custom Format hh:mm doesn't work, because the resulting figures are shown as a date.

Can anyone please help?