2. Prime Factors Friday, 19 February 2016 Objective Write a number as a product of its prime factors. Find the HCF and LCM of two numbers

3. 12 ÷ 2 = 6 12 ÷ 3 = 4 12 ÷ 6 = 2 12 can be divided by 2, 4 and 6 so 12 is not a prime number. 7 ÷ 7 = 1 7 ÷ 1 = 7 Prime Numbers A prime number is a number that can only be divided (exactly) by itself and 1. 7 can only be divided by itself and 1 to give an integer answer. 7 is a prime number

4. Write down the prime numbers between 1 and 40. 12345678910 11121314151617181920 21222324252627282930 31323334353637383940 12345678910 11121314151617181920 21222324252627282930 31323334353637383940

5. Factors Factors are the numbers that multiply together to give a certain number. The factor pairs of 12 are: 1 x 12 = 12 2 x 6 = 12 3 x 4 = 12 4 x 3 = 12 6 x 2 = 12 12 x 1 = 12

6. The prime factors of 12 are: 2 x 2 x 3 = 12 Prime numbers 12 2 6 3 2

7. Find the Highest Common Factor (HCF) of 36 and 72 1. Find the prime factors of both numbers 36 = 2 x 2 x 3 x 3 72 = 2 x 2 x 2 x 3 x 3 2. Use one of each of the numbers that are in both lists HCF = 2 x 2 x 3 x 3 HCF = 36

8. Find the Lowest Common Multiple (LCM) of 36 and 90 1. Find the prime factors of both numbers 36 = 2 x 2 x 3 x 3 90 = 2 x 3 x 3 x 5 2. Use one of each of the numbers that are in both lists and all the remaining numbers. LCM = 2 x 3 x 3 x 2 x 5 LCM = 180

9. 1. Find the HCF of 12 and 30. 2. Find the HCF of 54 and 180. 3. Find the LCM of 18 and 30. 4. Find the LCM of 24 and 84. 5. Find the LCM of 54 and 120 6. Find the LCM of 72 and 150 1. 6 2. 18 3. 90 4. 168