Least Common Multiple and Greatest Common Factor
Video Solutions to help Grade 6 students find the least common multiple and greatest common factor and apply factors to the Distributive
Plans and Worksheets for Grade 6
Plans and Worksheets for all Grades
Lessons for Grade 6
Common Core For Grade 6
New York State Common Core Math Module 2, Grade 6, Lesson 18
Lesson 18 Student Outcomes
• Students find the least common multiple and greatest common factor and apply factors to the Distributive
NYS Math Module 2 Grade 6 Lesson 18 Classwork
The Greatest Common Factor of two whole numbers a and b, written GCF(a, b), is the greatest whole number, which is
a factor of both a and b.
The Least Common Multiple of two nonzero numbers a and b, written LCM(a, b), is the least whole number (larger than
zero), which is a multiple of both a and b.
Greatest Common Factor: Find the greatest common factor of 12 and 18.
• Listing these factors as pairs can help you not miss any. Start with one times the number.
• Circle all factors that appear on both lists.
• Place a triangle around the greatest of these common factors.
Least Common Multiple: Find the least common multiple of 12 and 18.
Exploratory Challenge 1: Factors and GCF
Find the greatest common factor of one of these pairs: 30,50; 30,45; 45,60; 42,70; 96,144.
a. There are 18 girls and 24 boys who want to participate in a Trivia Challenge. If each team must have the same
number of girls and boys, what is the greatest number of teams that can enter? How many boys and girls will be on
b. The Ski Club members are preparing identical welcome kits for the new skiers. They have 60 hand warmer packets
and 48 foot warmer packets. What is the greatest number of kits they can prepare using all of the hand warmer
and foot warmer packets?
c. There are 435 representatives and 100 senators serving in the United States Congress. How many identical groups
with the same numbers of representative and senators could be formed from all of Congress, if we want the largest
d. Is the GCF of a pair of numbers ever equal to one of the numbers? Explain with an example.
e. Is the GCF of a pair of numbers ever greater than both numbers? Explain with an example.
Exploratory Challenge 2: Multiples and LCM
Find the least common multiple of one of these pairs: 9,12; 8,18; 4,30, 12,30; 20,50
a. Hot dogs come packed 10 in a package. Hot dog buns come packed 8 in a package. If we want one hot dog for
each bun for a picnic, with none left over, what is the least amount of each we need to buy?
b. Starting at 6:00 a.m., a bus makes a stop at my street corner every 15 minutes. Also starting at 6:00 a.m., a taxi
cab comes by every 12 minutes. What is the next time there will be a bus and a taxi at the corner at the same
c. Two gears in a machine are aligned by a mark drawn from the center of one gear to the center of the other. If
the first gear has 24 teeth and the second gear has 40 teeth, how many revolutions of the first gear are needed
until the marks line up again?
d. Is the LCM of a pair of numbers ever equal to one of the numbers? Explain with an example.
e. Is the LCM of a pair of numbers ever less than both numbers? Explain with an example.
Exploratory Challenge 3: Using Prime Factors to Determine GCF
Factor Tree Game
Exploratory Challenge 4: Applying Factors to the Distributive Property
Find the GCF from the two numbers and rewrite the sum using the Distributive Property
Distinguish between GCF and LCM
Find GCF using the factor tree.
GCF and the Distributive Property
LCM, GCF and the Distributive Property
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