Quantile® Resource Overview Finding the Least Common Denominator Resource Title: Quantile Skill and Concept: • Compare and order fractions using renaming strategies (QSC155) • Find multiples, common multiples, and the least common multiple numbers; explain. (QSC221) Quantile Measure: 710Q Excerpted from: The Math Learning Center PO Box 12929, Salem, Oregon 97309-­‐0929 www.mathlearningcenter.org ©Math Learning Center For access to other free resources, visit www.Quantiles.com. The Quantile® Framework for Mathematics, developed by educational measurement and research organization MetaMetrics®, comprises more than 500 Quantile Skills and Concepts taught from kindergarten through high school. The Quantile Framework depicts the developmental nature of mathematics and the connections between mathematics content. By matching a student's Quantile measure with the Quantile measure of a mathematical skill or concept, you can determine if the student is ready to learn that skill, needs reinforcement in supporting concepts first, or whether enrichment would be appropriate. For more information and to use free Quantile utilities, visit www.Quantiles.com. 1000 Park Forty Plaza Drive, Suite 120, Durham, North Carolina 27713 METAMETRICS®, the METAMETRICS® logo and tagline, QUANTILE®, QUANTILE FRAMEWORK® and the QUANTILE® logo are trademarks of MetaMetrics, Inc., and are
registered in the United States and abroad. The names of other companies and products mentioned herein may be the trademarks of their respective owners.
Set A6 Numbers & Operations: Fraction Concepts Blackline Use anytime after Set 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 least common multiple 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
number so the denominators are equal.
2 × 5 = 10 3×5
15
4 × 3 = 12 5 × 3 15
4 is greater than 2 by exactly 2
5
3
15
1 Find the least common multiple (LCM) of each pair of numbers.
ex. 4 and 10
a
b
5 and 6
2 and 7
4, 8, 12, 16, 20
10, 20
20 is the LCM of 4 and 10
2Circle 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 information from problem 1 to help. Put a star by the fraction that turns out to be greater.
ex.
3
4
7
10
15
3 x 5 = 20
4x5
14
7x2
=
10 x 2 20
a
4
5
5
6
b
1
2
4
7
(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.)
3Find the least common multiple (LCM) of each pair of numbers.
a
b
5 and 10
c
6 and 9
5 and 7
4Circle 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 information from problem 3 to help. Put a star by the fraction that turns out to be greater.
a
2
5
b
3
10
5Erica swam
6
8
4
6
c
7
9
4
5
5
7
10
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
6, 12, 18, 24, 30
30 is the LCM of 5 and 6
4
5
6 24
=
6 30
5
6
5 25
=
5 30
25
24
>
30
30
2, 4, 6, 8, 10, 12, 14
7, 14, 21
14 is the LCM of 2 and 7
1
2
7
7
=
7 14
4
7
2
8
=
2 14
8
7
>
14
14