Arithmetic Grade Four
Lesson Ninety-eight: Subtracting Mixed Numbers
If you can add mixed numbers, you can subtract them too. Here are the basic
steps involved in subtracting mixed numbers with unlike denominators.
Sample Problem: 3 3/4 -
2 1/8.
Step One: Find LCD. The LCD of 4 and 8 is 8.
Step Two: Convert fractions. Change 3/4 to 6/8 and 1/8 is
fine the way it is since it already has a denominator of 8.
Step Three: Subtract whole numbers.
3 6/8 - 2 1/8 =
1 + ( 6/8 - 1/8 ).
Step Four: Subtract the fractions.
1 + 5/8.
Step Five:
Reduce the fraction (if necessary) 1 5/8.
ANSWER: 1 5/8.
Here's another example:
Sample Problem: 3 5/6 -
1 1/4.
Step One: Find LCD. The LCD of 6 and 4 is 12.
Step Two: Convert fractions. Change 5/6 to 10/12 and change
1/4 to 3/12.
Step Three: Subtract whole numbers.
3 10/12 - 1 3/12 =
2 + ( 10/12 - 3/12 ).
Step Four: Subtract the fractions.
2 + 7/12.
Step Five:
Reduce the fraction (if necessary) 2 7/12.
ANSWER: 2 7/12.
Now you get to try a few for yourself.
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