Arithmetic Grade Six

Lesson Thirty-four: Subtracting Hours and Minutes

Sometimes the minutes in the top time are less than the minutes in the bottom time. Think about what you would do with this problem: 


	  5:20
	- 3:40
	------
As you probably figured out, it will be necessary to borrow in order to complete this problem.

We know that 1 hour is equal to 60 minutes and so we can regroup by borrowing one hour in the hour's column and adding 60 to the minute's column like this: 


	  4:80
	- 3:40
	-------
	  1:40
Here's another example: 

	  4:15
	- 2:25
	-------
After borrowing 1 hour and increasing the value in the minutes column by 60, we get: 

	  3:75
	- 2:25
	-------
It's easy to solve the problem once borrowing is done. The answer to this problem is 1:50.

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