**1. Least Common Multiple (LCM)**:

The least common multiple of a group of numbers is the smallest positive integer which is divisible by all the numbers in the group.

The multiples of 6: 6, 12, 18, **24**, 30, 36, 42, **48**, 54, 60, …

The multiple of 8: 8, 16, **24**, 32, 40, **48**, 56, 64, 72, 80, …

24 and 48 are the first two common multiples of 6 and 8. Since 24 is the least of all common multiples, we say the least common multiple (LCM) of 6 and 8 is 24.

**2. Methods to find LCM**

- Using prime factorization. LCM is obtained by multiplying the highest power of each prime factor of the given numbers. Teaching on whiteboard in the class.
- Continuous division. Teaching on whiteboard in the class.
- Venn diagram. Teaching on whiteboard in the class.

**3. Why LCM?**

- adding, subtracting, or comparing vulgar fractions, it is useful to find the
**least common multiple**of the denominators, often called the lowest common denominator, because each of the fractions can be expressed as a fraction with this denominator. Ex. 1/15 + 1/18 + 1/21 - Word problems: Teaching on whiteboard in the class

**4. Home Work:**

- Handout: two pages
- Workbook:
- page 2: 7
- Page 3: 13, 15(a), 15(b)(ii), 17(a), 17(b)(ii)
- Page 4: 23
- Page 5: 24