How can I use sexagesimal in Calc, as in time calculations

I frequently use elapsed time in calculations and would like to see it expressed in sexagesimal notaton ##:##:##. Many spreadsheets try to shoehorn numbers expressed this way into a date/time format that is stored as a number relative to a given date and time which distorts the calculations.

How about the Time format code [HH]:MM:SS? Calculated in fractions of a day, 1.23 is displayed as 29:31:12, i.e. 29 hours, 31 minutes, 12 seconds.

Number Format Codes

Many spreadsheets try to shoehorn numbers expressed this way into a date/time format that is stored as a number relative to a given date and time which distorts the calculations.

Calc is one of these. There’s no built-in methods that you want.

Note that using time format (fraction of a day) has precision millions of times greater than seconds (for times), so you likely could safely use it for the calculations. Also note that using duration format string (using square brackets, as @EarnestAl suggested) rounds the displayed time (as opposed to wall clock time formats not using them), so you won’t have issues when a tiny deviation due to floating-point calculation would make your time look off by one second.

Thank you, Earnest Al and Mike Kaganski. Dividing the hours by 24 and using the TIME format [HH]:MM:SS as Al suggested did the trick. I am grateful to you gentlemen! Thank you.