Arithmetic Grade Four
Lesson One hundred and fifty-two: Subtracting Time
Subtracting time is fairly easy, most of the time. The trick is when you
have to borrow from the hours column. For instance, consider this problem:
As you can see, 15 minus 46 just isn't going to work. You must borrow from
the hours column. When you do this, you need to remember that one hour
is worth 60 minutes! So, your revised problem will look like:
Now it's just a simple matter of 2 minus 1 and 75 minus 46, which yields an answer
of 1:29.
As a warm up you get to do a few problems which don't require regrouping.
Click here to go to next page