1. Saturday, 09 September 2006 ©RSH Number Prime Numbers and Prime factors

2. Saturday, 09 September 2006 ©RSH Prime Numbers A prime number has exactly 2 factors, 1 and itself. 1 is not a prime number. The first five prime numbers are: 2, 3, 5, 7, and Prime Numbers A prime number has exactly 2 factors, 1 and itself. 1 is not a prime number. The first five prime numbers are: 2, 3, 5, 7, and Notes 11 Prime numbers are used in computer security – for passwords and credit cards !

3. Saturday, 09 September 2006 ©RSH Prime Factors The factors of 12 are: 1, 2, 3, 4, 6, 12 The prime factors of 12 are 2 and 3 because these are the only prime numbers in the list. Prime Factors The factors of 12 are: 1, 2, 3, 4, 6, 12 The prime factors of 12 are 2 and 3 because these are the only prime numbers in the list. Notes

4. Saturday, 09 September 2006 ©RSH Exercise 1.Write down all the prime numbers between 10 and 30. 2.Write down two prime numbers which add up to another prime. 11, 13, 17, 19, 23, 29 2 + 3 = 5 or 2 + 5 = 7 3.Write down the prime factors of 8. 2