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: __________________

MMC Topic 2 Number Theory: Divisibility Rules and Prime Numbers 2

Problem Sets: Divisibility Rules

Is the Number to the left of each row divisible by the Number at the top of each column? Write YES or NO in the boxes.

2 3 4 5 6 9 69 70 21 92 74 25 10 15 75 22 225 480 422 567 918 711

MMC Topic 2 Number Theory: Divisibility Rules and Prime Numbers 3

Group Activity: Divisibility Rules How many prime numbers are there from 1-100? ________________

Circle the prime numbers.