Math 6H ( Periods 3, 6, & 7)

Addition and Subtraction of Mixed Numbers 7-2

Although the textbook states that to add or subtract mixed numbers you can first change the mixed numbers to improper fractions and then use the methods of Section 7-1, I want you to practice the methods taught in class this week.

I want you to stack you mixed numbers, separating the fractional parts from the whole numbers. Proceed to add ( or subtract) the fractional parts, using LCD-- where necessary. At times you will need to borrow from the whole number to be able to subtract properly.

3 4/9 + 1 7/9

stack

3 4/9
+1 7/9
4 11/9 = 5 2/9


9 3/7 - 4 5/7

9 3/7
-4 5/7

need to change to
8 10/7
-4 5/7
4 5/7

Again, if the fractional parts of the given mixed numbers have different denominators, we find equivalent mixed numbers whose fractional parts have the same denominator-- usually the LCD