unit 4 – gcf and lcm greatest common factor least common multiple

Unit 4 – GCF and LCMGreatest Common Factor

Least Common Multiple

Objective: As a result in learning, students should be able to distinguish between prime and composite numbers and list the factors of a given number.

Warm Up:Which number is prime?

9 61 102 363

• What is the difference between a prime and a composite number?

• What is a factor?• What strategies can you use to find the

factors of a number?• Take WWAK• Use Making Rectangles handout• HW: Prime and Composite Coloring

handout

composite number

A number with more than two factors.

factor A number multiplied by another number to get a product.

prime number

A number with exactly two factors, 1 and itself.

Objective: As a result in learning, students should be able to distinguish between prime and composite numbers and list the factors of a given number.

Warm up: Find all the factors of 28. Circle the prime numbers.

•Factors and prime factorization Check-up Handout•Play the factor game (49)•HW:

Objective: As a result in learning, students should be able to find the greatest common factor of two numbers

Warm Up:What does “greatest common factor” mean?

greatest common factor

The largest common factor of two or more given numbers.

•GCF notes• Finding GCF•HW: Most Wanted Poster

Objective: As a result in learning, students should be able to find the greatest common factor of two numbers.

Warm Up:Your table has two pieces of string that you need to cut. One piece of string is 36 inches and the other is 80 inches. Cut all the string into pieces of equal lengths. What is the greatest possible length of each piece?

Angie works in a pet store. She needs to divide 36 angelfish, 42 rainbow fish, and 126 goldfish into aquariums so that each aquarium has the same number of each type of fish, and there are no fish left over. What is the greatest number of aquariums Angie can fill under these conditions?

There are 12 boys and 18 girls in Mr. Ruiz's science class. The students must form lab groups. Each group must have the same number of boys and the same number of girls. What is the greatest number of groups Mr. Ruiz can make if every student must be in a group?

Ms. Spain and Mr. France have donated a total of 90 hot dogs and 72 bags of chips for the class picnic. Each student will receive the same amount of refreshments. All refreshments must be used. • What is the greatest number of students

that can attend the picnic? • How many bags of chips will each student

receive? • How many hotdogs will each student

receive?

The elementary school lunch menu repeats every 20 days; the middle school lunch menu repeats every 15 days. Both schools are serving pizza today. In how many days will both schools serve pizza again?

Ultimate Challenge Problems

Objective: As a result in learning, students should be able to find the least common multiple of two numbers.

Warm Up:Markers are sold in packs of 6. Pens are sold in packs of 2. There are 30 students in the class. What is the least number of packs the teacher should buy so that each student has a marker and a pen with none left over?

least common multiple

The smallest number, other than zero, that is a multiple of two or more given numbers.

• What is a multiple? • How can you determine the multiples two numbers have in

common? • As a review of multiples, the students will do a quick activity called

"Hundred Chart Multiples." • Place a basket of Unifix cubes at each group of students. • Give each student a hundreds chart. • Begin with two numbers such as 2 and 6. • Students use one color cube to cover all the multiples of 2 up to

50. • Students use another color cube to cover all the multiples of 6 up

to 50. • Lead the students in a discussion of how the common multiples of

2 and 6 are the numbers with two cubes on them. • Students will then be able to identify the least common multiple.

(the least common multiple of 2 and 6 is 12) • Clear the boards and repeat the process using other numbers.

Methods to finding LCM handoutHW:

Objective: As a result in learning, students should be able to solve problems involving GCF and LCM.

Warm Up:What is the LCM of 12 and 8?

Two students are building blocks. Reece's blocks are 4 cm high, and Maddy's blocks are 9 cm high. How tall will their stacks be when they are the same height for the first time?

Pam is making fruit baskets. She has 30 apples, 24 bananas, and 12 oranges. What is the greatest number of baskets she can make if each type of fruit is distributed equally among the baskets?

LCM PracticeRiddle Me This

Objective: As a result in learning, students should be able to solve problems involving GCF and LCM.

Classifying NumbersProduct Game

Objective: As a result in learning, students should be able to solve problems involving GCF and LCM.

Word Problem Challenge

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