2. Least Common Multiple Created by Cristina Salas Leal November 15, 2007

3. Objective The students will identify multiples of positive whole numbers and find the least common multiple in the set. TEKS (6.1F) The student is expected to identify multiples of a positive integer and common multiples and the least common multiple of a set of positive integers.

4. Math Journal Take a few minutes to write the question and respond. What does LCM stand for? What is a multiple? When is the LCM used in the real world?

5. What is a multiple? A multiple of a number is its product of that number with a whole number. Example 4 x 1 = 4 4 x 2 = 8 4 x 3 = 12 4 x 4 = 16 4 x 5 = 20 multiples of 4: 4, 8, 12, 16, 20

6. What is LCM? LCM – Least Common Multiple The least common multiple is the least multiple that two more numbers have in common.

7. Find the LCM of 6 and 8 Step 1 – List the multiples of 6 multiples of 6: 6, 12, 18, 24, 30, 36, … Step 2 – List the multiples of 8 multiples of 8: 8, 16, 24, 32, 40, 48, … Step 3 – Find the common multiples 6: 6, 12, 18, 24, 30, 36, … 8: 8, 16, 24, 32, 40, 48,... Step 4 – The LCM of 6 and 8 is 24

8. Birthday Party Cindy is having a birthday party. She must buy plates, cups and napkins. Plates come in a pack 25. Cups come in a pack of 20 and napkins come in pack of 100. Cindy wants to have the same number of each. How many packages of cups, napkins and plates should she buy?

9. Birthday Party Problem Cont… What information is given? Cups – 20-pack Plates – 25-pack Napkins – 100-pack

10. Find the LCM 1 pack2 packs3 packs4 packs5 packs Cups20406080100 Plates255075100125 Napkins100200300400500

11. Birthday Party problem cont…. Cindy would need to buy 5 packages of cups 4 packages of plates 1 package of napkins

12. Internet Websites Match the answer to the problem on this website. Check to see how many you answered correctly. Click here - LCMLCM Test your self. How many LCM problems can you answer in 60 seconds? Click here – aaamath aaamath Scroll down - Play the Countdown Game

13. Thank You