Adding and Subtracting Time
Adding Times
Follow these steps:
- Add the hours
- Add the minutes
- If the minutes are 60 or more, subtract 60 from the minutes and add 1 to hours
Easy example: What is 2:45 + 1:10 ?
Add the Hours: 2+1 = 3
Add the Minutes: 45+10 = 55
The minutes are ok, so the answer is 3:55
Hard example: What is 2:45 + 1:20 ?
Add the Hours: 2+1 = 3
Add the Minutes: 45+20 = 65
The minutes are 60 or more, so subtract 60 from minutes (65-60 = 5 Minutes) and add 1 to Hours (3+1 = 4 Hours) ... so the answer is 4:05
Subtracting Times
Follow these steps:
- Subtract the hours
- Subtract the minutes
- If the minutes are negative, add 60 to the minutes and subtract 1 from hours.
(Note: the easiest way to add 60 to the negative minutes is to start with 60 and subtract the minutes)
Easy example: What is 4:10 - 1:05 ?
Subtract the Hours: 4-1 = 3
Subtract the Minutes: 10-5 = 5
The minutes are fine, so the answer is 3:05
Hard example: What is 4:10 - 1:35 ?
Subtract the Hours: 4-1 = 3
Subtract the Minutes: 10-35 = -25
The minutes are less than 0, so add 60 to Minutes (-25+60 = 60-25 = 35 Minutes) and subtract 1 from Hours (3-1 = 2 Hours) ... answer is 2:35
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