Addition of Time

How to add hours and half-hours to a time:

  • Add the number of minutes together. If the minutes are 60 or more, subtract 60 from the minutes and increase the number of hours by one.
  • Add the number of hours to the hours portion of the time.
  • If the number of hours is more than 12 do the following:
    • Subtract 12 from the number of hours.
    • If the time was AM change it to PM, if it was PM change it to AM.
    • Repeat this process if the number of hours is still more than 12.
  • If the number of hours is equal to 12 change AM to PM or PM to AM.

Example: What time is 17 hours and 30 minutes after 3:30 AM?

  • The sum of the minutes equals 60. Subtract 60 from the minutes and increase the hours by one to 18.
  • Add the hours together. (18 hours + 3 hours = 21 hours)
  • If the number of hours is more than 12 do the following:
    • Subtract 12 from the number of hours. (21 hours - 12 hours = 9 hours)
    • Change the AM to PM.
  • Answer: 9:00 PM


What is the Sum of the times?
 

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Copyright (C) 2004 J. Banfill. All Rights Reserved.