MMC Topic 2 Number Theory: Divisibility Rules and Prime Numbers 1 Divisibility Rules and Prime Numbers I. Divisibility Rules: 2: last digit is 0,2,4,6 or 8 3: sum of digits is divisible by 3 4: two-digit number formed by the last two digits is divisible by 4 5: last digit is 0 or 5 6: number is divisible by both 2 and 3 8: three-digit number formed by the last 3 digits is divisible by 8 9: sum of digits is divisible by 9 10: last digit is 0 II. Prime Numbers • A prime number is a number that has only two factors: 1 and itself. • For example, 2 is a prime number. Its factors are 2 and 1. Questions • Is 1 a prime number? • What do we call numbers that have more than 2 factors? Name: _________________ Date: __________________