Quantile® Resource Overview

Resource Title: Finding the Least Common Denominator

Quantile Skill • Compare and order using renaming and Concept: strategies (QSC155) • Find multiples, common multiples, and the least

common ; explain. (QSC221)

Quantile Measure: 710 Q

Excerpted from:

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Set A6 Numbers & Operations: Concepts Blackline Use anytime after A6, Activity 2. Run a class set. name date Set A6 H Independent Worksheet 2

Independent Worksheet

Finding the Least Common Denominator

2 4 Which is greater, 3 or 5 ? Exactly how much difference is there between these two fractions? If you want to compare, add, or subtract two fractions, it is easier if you rewrite them so they both have the same denominator. To do this: • Find the of the denominators of the fractions. multiples of 3 3, 6, 9, 12, 15 multiples of 5 5, 10, 15 The least common multiple of 3 and 5 is 15.

• Multiply the numerator and denominator of each fraction by the same so the denominators are equal. 2 × 5 = 10 4 × 3 = 12 4 is greater than 2 by exactly 2 3 × 5 15 5 × 3 15 5 3 15 1 Find the least common multiple (LCM) of each pair of numbers. ex. 4 and 10 a 5 and 6 b 2 and 7 4, 8, 12, 16, 20 10, 20 20 is the LCM of 4 and 10 2 Circle the fraction you think is greater in each pair. Then find out for sure by re- writing the fractions so they have common denominators. Hint: Use the informa- tion from problem 1 to help. Put a star by the fraction that turns out to be greater. ex. 3 7 a 4 5 b 1 4 4 10 5 6 2 7 3 x 5 15 = 4 x 5 20 7 x 2 14 = 10 x 2 20 (Continued on back.) © The Math Learning Center Bridges in Mathematics Grade 5 Supplement • A6.21 Set A6 Numbers & Operations: Fraction Concepts Blackline Run a class set.

Independent Worksheet 2 Finding the Least Common Denominator (cont.)

3 Find the least common multiple (LCM) of each pair of numbers. a 5 and 10 b 6 and 9 c 5 and 7

4 Circle the fraction you think is greater in each pair. Then find out for sure by rewriting the fractions so they have common denominators. Hint: Use the informa- tion from problem 3 to help. Put a star by the fraction that turns out to be greater. a 2 3 b 4 7 c 4 5 5 10 6 9 5 7

6 10 5 Erica swam 8 of a mile on Monday. She swam 12 of a mile on Tuesday. Did she swim farther on Monday or Tuesday. Exactly how much farther? Use numbers, words, and/or labeled sketches to solve this problem. Show all your work.

Erica swam exactly ______of a mile farther on ______.

A6.22 • Bridges in Mathematics Grade 5 Supplement © The Math Learning Center (Key)

5, 10, 15, 20, 25, 30, 35 2, 4, 6, 8, 10, 12, 14 6, 12, 18, 24, 30 7, 14, 21 30 is the LCM of 5 and 6 14 is the LCM of 2 and 7

4 6 24 1 7 7 = = 5 6 30 2 7 14 25 24 8 7 > > 14 14 5 5 25 30 30 4 2 8 = = 6 5 30 7 2 14