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Greatest Common Factor & Least Common Multiple
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 We'll learn how to find the Greatest Common Factor.
 We'll also learn how to find the Least Common Multiple.
 And we'll see how this knowledge can help us plan a barbecue, play sports, and even race cars!

Discussion Questions
 Before VideoWhat is a factor?ANSWER
A factor of a number is a whole number that, when multiplied by another whole number, equals the original number. For example, 4 and 2 are factors of 8 because 4 × 2 = 8.
10: 1, 2, 5, 10. 8: 1, 2, 4, 8. 2 is a common factor.
A multiple of a number, n, is a number that I can find by multiplying n by a whole number.
4: 4, 8, 12, 16, 20, 24, …; 6: 6, 12, 18, 24, 30, 36, …; both lists have 12 and 24.
I could color in squares on a number chart. I count skip count on a number line.
 After VideoWhat is a greatest common factor (GCF)?ANSWER
The GCF of two numbers is the greatest number that is a factor of both numbers.
Yes, two numbers may have no factors in common except 1, like 2 and 3.
The LCM of two numbers is the least number that is a multiple of both numbers.
When I look at the two lists of multiples, the LCM is the first number that the lists have in common.
I can look for key division words for GCF, such as "split evenly" or "equal groups" and size words like "greatest" and "maximum." For LCM, I can look for key multiplication words like "repeatedly" and size words like "least" and "minimum."

Vocabulary
 Factor DEFINE
A factor of a number, n, is a whole number that, when multiplied by another whole number, equals n.
 Factor pair DEFINE
A factor pair of a number is a pair of factors whose product equals the number.
 Multiple DEFINE
A multiple of a number n is a number that can be found as a product of n and another whole number.
 Common factor DEFINE
A common factor of a set of numbers is a number that is a factor of every number in the set.
 Common multiple DEFINE
A common multiple of a set of numbers is a number that is a multiple of every number in the set.
 Greatest common factor DEFINE
The greatest common factor of a set of numbers is the greatest number that is a factor of all numbers in the set.
 Least common multiple DEFINE
The least common multiple of a set of numbers is the least number that is a multiple of all numbers in the set.
 Factor DEFINE

Reading Material

Practice Word Problems

Practice Number Problems

Lesson Plan

Teacher Guide