Chapter 3 Adding and Subtracting Fractions 2010 Pearson

Chapter 3 Adding and Subtracting Fractions © 2010 Pearson Education, Inc. All rights reserved.

3. 4 Adding and Subtracting Mixed Numbers Objectives 1. Estimate an answer, then add or subtract mixed numbers. 2. Estimate an answer, then subtract mixed numbers by regrouping. 3. Add or subtract mixed numbers using an alternate method. Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 2

Add or subtract mixed numbers by adding or subtracting the fraction parts and then the whole number parts. It is a good idea to estimate the answer first. Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 3

Parallel Example 1 Adding and Subtracting Mixed Numbers First estimate the answer. Then add or subtract to find the exact answer. Estimate Exact a. Rounds to Sum of whole numbers. Copyright © 2010 Pearson Education, Inc. All rights reserved. Sum of fractions. Slide 3. 4 - 4

Parallel Example 1 Adding and Subtracting Mixed Numbers First estimate the answer. Then add or subtract to find the exact answer. b. Estimate Exact 30 is the least common denominator. Rounds to Subtract whole numbers. Copyright © 2010 Pearson Education, Inc. All rights reserved. Subtract fractions. Slide 3. 4 - 5

Parallel Example 2 Simplify and Regroup When Adding Mixed Numbers First estimate, and then add Estimate Exact Rounds to Sum of whole numbers. Becomes Sum of fractions. Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 6

Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 7

Parallel Example 3 Regroup When Subtracting Mixed Numbers a. First estimate, and then subtract. Estimate Exact Rounds to Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 8

Parallel Example 3 Regroup When Subtracting Mixed Numbers b. First estimate, and then subtract. Estimate Exact Rounds to Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 9

Parallel Example 3 Regroup When Subtracting Mixed Numbers First estimate, and then subtract. Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 10

An alternate method for adding or subtracting mixed numbers is to first change the mixed numbers to improper fractions. Then, rewrite the unlike fractions as like fractions. Finally, add or subtract the numerators and write the answer in lowest terms. Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 11

Parallel Example 4 Adding or Subtracting Mixed Numbers Using an Alternate Method Add. 6 is the least common denominator Change to improper fractions. Mixed number Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 12

Parallel Example 4 continued Adding or Subtracting Mixed Numbers Using an Alternate Method Subtract. 15 is the least common denominator Change to improper fractions. Mixed number Copyright © 2010 Pearson Education, Inc. All rights reserved. Slide 3. 4 - 13