Tutoring Colleagues

I am always surprised when no one shows up on Xmas Day, since School has such a multicultural student body – Muslims and Buddhists and atheists and whatnot.

Today I tutored my colleague!

What fun.

Working on monthly time sheets – Dec 25 usually happens very close to the end of the  month – and someone asked me how to add up hours &  minutes.

“Hours are easy enough, but I have to add up the minutes by calculator and figure the hours + minutes left over, then add the hours to my hours total – it’s so complicated!”

Computers love this sort of complex math.

Here is a pic of my sample spreadsheet:

hours numbers

And here is the relevant part showing the math formulas:

hours formula

Green box:

  • Total Minutes: In cell F7, add the total minutes. By the end of the month, that’s usually more than 60, more than 120, more than 180.
  • Minutes:Hours: INT(F7/60):  divide my total minutes by 60 (the number of minutes in an hour) and give me the whole number that results.
  • Minutes:Mins:  MOD(F7,60):  This formula does not use the / for division, for extra confusion maybe. Divide my total minutes by 60, and give me the remainder.


Total Hours:

  • Hours: Add the hours in the column, then add the whole number from the green box.
  • Minutes: Don’t add the minutes, that was taken care of in the green box.  Instead, copy the remainder from the green box.

Copy this spreadsheet page to a new page for the new month. Erase the hourly information and…

watch the math do itself as you enter new numbers.

Better yet – make it a template that you can copy from month to month.

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