Adding hours and minutes

Carry at sixty, not at one hundred

Add the minutes first; every full 60 carries into the hours column. 2 h 45 min plus 1 h 30 min is 4 h 15 min because 75 minutes carries one hour.

Decimal hours divide minutes by 60

Payroll and billing systems multiply hours by a rate, so minutes must become sixtieths. The common shortcuts are worth memorizing.

When in doubt, work entirely in minutes

Converting every entry to minutes, adding once, and converting back removes carrying mistakes. That is exactly what the calculator does internally.

Check your total: a result whose minutes are 60 or more was carried incorrectly somewhere.