The document discusses the least common multiple (LCM) and how it can be used to find common denominators when adding or comparing fractions. It explains that the LCM is the smallest number that is a multiple of both numbers being considered. If the numbers are prime, their LCM is found by multiplying them together. Examples are provided to illustrate calculating the LCM of various number pairs and groups.

1. FRACTIONS Least Common Multiple

2. Using What You Know . . . GREATEST COMMON FACTOR Helps Reduce fractions L EAST C OMMON M ULTIPLE Helps find Common Denominators

3. Using What You Learned . . . What’s the LCM ?? What is the first multiple that they both share? 4 – 4, 8, 12, 16 . . . 3 – 3, 6, 9, 12, 15 . . . L EAST C OMMON M ULTIPLE Helps find Common Denominators

4. Least Common Multiple 5 20 THINK . . . L east . . . The smallest possible C ommon . . . They both have it M ultiple . . . A multiple of both numbers

5. Least Common Multiple HINT The LCM will ALWAYS be EQUAL to Or GREATER than the largest of the two (or three numbers)

6. Least Common Multiple 3 and 7 5 and 7 11 and 13 All of these numbers are PRIME . IF both numbers are PRIME, just multiply them together.

7. Least Common Multiple 3 and 7 5 and 7 11 and 13 All of these numbers are PRIME . IF both numbers are PRIME, just multiply them together. 21 35 141

8. Give It A Try – What’s the LCM? 3 and 5 12 and 20 5, 3, and 7 3 and 9 4 and 12 6 and 7 5 and 6 3 and 4 6 and 9 10 and 100 15 60 105 9 12 42 30 12 9 100