5-5 Least Common Multiple Warm Up Problem of the Day Course 1 Warm Up Problem of the Day Lesson Presentation

5-5 Least Common Multiple Warm Up Course 1 5-5 Least Common Multiple Warm Up Write the first five multiples of each number. 1. 5 2. 6 3. 10 4. 12 5, 10, 15, 20, 25 6, 12, 18, 24, 30 10, 20, 30, 40, 50 12, 24, 36, 48, 60

5-5 Least Common Multiple Problem of the Day Course 1 5-5 Least Common Multiple Problem of the Day Greg, Sam and Mary all work at the same high school. One of them is a principal, one of them is a teacher, and one of them is a janitor. Sam is older than Mary. Mary does not live in the same town as the principal. The teacher, the oldest of the three, often plays golf with Greg. What is each person’s job. Greg, principal; Sam, teacher; Mary, janitor

5-5 Least Common Multiple Course 1 5-5 Least Common Multiple Learn to find the least common multiple (LCM) of a group of numbers.

Insert Lesson Title Here Course 1 5-5 Least Common Multiple Insert Lesson Title Here Vocabulary least common multiple (LCM)

Additional Example 1: Consumer Application Course 1 5-5 Least Common Multiple Additional Example 1: Consumer Application English muffins come in packs of 8, and eggs in cartons of 12. If there are 24 students, what is the least number of packs and cartons needed so that each student has a muffin sandwich with one egg and there are no muffins left over? Draw muffins in groups of 8. Draw eggs in groups of 12. Stop when you have drawn the same number of each. There are 24 English muffins and 24 eggs. So 3 packs of English muffins and 2 cartons of eggs are needed.

5-5 Least Common Multiple Try This: Example 1 Course 1 5-5 Least Common Multiple Try This: Example 1 Dog cookies come in packages of 6, and bones in bags of 9. If there are 18 dogs, what is the least number of packages and bags needed so that each dog has a treat box with one bone and one cookie and there are no bones or cookies left over? Draw cookies in groups of 6. Draw bones in groups of 9. Stop when you have drawn the same number of each. There are 18 dog cookies and 18 bones. So 3 packages of dog cookies and 2 bags of bones are needed.

5-5 Least Common Multiple Course 1 5-5 Least Common Multiple The smallest number that is a multiple of two or more numbers is the least common multiple (LCM). In Additional Example 1, the LCM of 8 and 12 is 24.

Additional Example 2A: Using Multiples to Find the LCM Course 1 5-5 Least Common Multiple Additional Example 2A: Using Multiples to Find the LCM Find the least common multiple (LCM). Method 1: Use a number line. A. 3 and 4 Use a number line to skip count by 3 and 4. 0 2 4 6 8 10 12 The least common multiple (LCM) of 3 and 4 is 12.

Additional Example 2B: Using Multiples to Find the LCM Course 1 5-5 Least Common Multiple Additional Example 2B: Using Multiples to Find the LCM Find the least common multiple (LCM). Method 2: Use a list. B. 4, 5, and 8 4: 4, 8, 12 , 16, 20, 24, 28, 32, 36, 40, 44, . . . List multiples of 4, 5, and 8. 5: 5, 10, 15, 20, 25, 30, 35, 40, 45, . . . 8: 8, 16, 24, 32, 40, 48, . . . Find the smallest number that is in all the lists. LCM: 40

5-5 Least Common Multiple Remember! Course 1 5-5 Least Common Multiple The prime factorization of a number is the number written as a product of its prime factorization. Remember!

Additional Example 2C: Using Multiples to Find the LCM Course 1 5-5 Least Common Multiple Additional Example 2C: Using Multiples to Find the LCM Find the least common multiple (LCM). Method 3: Use prime factorization. C. 6 and 20 6 = 2 • 3 Write the prime factorization of each number. 20 = 2 • 2 • 5 Line up the common factors. 2 • 3 • 2 • 5 To find the LCM, multiply one number from each column. 2 • 3 • 2 • 5 = 60 LCM: 60

Additional Example 2D: Using Multiples to Find the LCM Course 1 5-5 Least Common Multiple Additional Example 2D: Using Multiples to Find the LCM Find the least common multiple (LCM). D. 15, 6, and 4 15 = 3 • 5 Write the prime factorization of each number in exponential form. 6 = 3 • 2 2 4 = 2 To find the LCM, multiply each prime factor once with the greatest exponent used in any of the prime factorizations. 2 3 • 5 • 2 2 3 • 5 • 2 = 60 LCM: 60

5-5 Least Common Multiple Try This: Example 2A Course 1 5-5 Least Common Multiple Try This: Example 2A Find the least common multiple (LCM). Method 1: Use a number line. A. 2 and 3 Use a number line to skip count by 2 and 3. 0 1 2 3 4 5 6 The least common multiple (LCM) of 2 and 3 is 6.

5-5 Least Common Multiple Try This: Example 2B Method 2: Use a list. Course 1 5-5 Least Common Multiple Try This: Example 2B Find the least common multiple (LCM). Method 2: Use a list. B. 3, 4, and 9 3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, . . . List multiples of 3, 4, and 9. 4: 4, 8, 12, 16, 20, 24, 28, 32, 36, … Find the smallest number that is in all the lists. 9: 9, 18, 27, 36, 45, . . . The least common multiple of 3, 4, and 9 is 36.

5-5 Least Common Multiple Try This: Example 2C Course 1 5-5 Least Common Multiple Try This: Example 2C Find the least common multiple (LCM). Method 3: Use prime factorization. C. 4 and 10 4 = 2 • 2 Write the prime factorization of each number. 10 = 2 • 5 Line up the common factors. 2 • 2 • 5 To find the LCM, multiply one number from each column. 2 • 2 • 5 = 20 LCM: 20

5-5 Least Common Multiple Try This: Example 2D LCM: 24 Course 1 5-5 Least Common Multiple Try This: Example 2D Find the least common multiple (LCM). D. 12, 6, and 8 12 = 22 • 3 Write the prime factorization of each number in exponential form. 6 = 2 • 3 8 = 23 To find the LCM, multiply each prime factor once with the greatest exponent used in any of the prime factorizations. 23 • 3 23 • 3 = 24 LCM: 24

5-5 Least Common Multiple Lesson Quiz Course 1 5-5 Least Common Multiple Lesson Quiz Find the least common multiple (LCM). 1. 6, 14 2. 9, 12 3. 5, 6, 10 4. 12, 16, 24, 36 5. Two students in Mrs. Albring’s preschool class are stacking blocks, one on top of the other. 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? 42 36 30 144 36 cm