Learn to use divisibility rules. 4.1 Divisibility

Vocabulary divisible composite number prime number

A number is divisible by another number if the quotient is a whole number with no remainder. 42 ÷ 6 =7Quotient

10,53615,99010 if the last digit is if the sum of the digits is divisible by if the number is divisible by both 2 and 3. 10,97814,9755 if the last digit is 0 or 5. 7,5188,5124 if the last two digits form a number divisible by if the sum of the digits is divisible by 3. 4,9753,9782 if the last digit is even (0, 2, 4, 6, or 8). Not DivisibleDivisibleA number is divisible by... Divisibility Rules

Division by 0 is undefined. Remember!

Additional Example 1A: Checking Divisibility Tell whether 462 is divisible by 2, 3, 4, and Not divisible So 462 is divisible by 2 and 3. The last digit, 2, is even. The sum of the digits is = is divisible by 3. The last two digits form the number is not divisible by 4. Divisible Not divisible The last digit is 2.

Additional Example 1B: Checking Divisibility Tell whether 540 is divisible by 6, 9, and So 540 is divisible by 6, 9, and 10. The number is divisible by both 2 and 3. The sum of the digits is = 9. 9 is divisible by 9. The last digit is 0. Divisible

Composite numbers a number that has more than two factors. Ex: 6 is divisible by 6 and 1 and also by 3 and 2. Its factors are 6, 1, 3 & 2 A prime number a number that has exactly two factors, itself and 1. Ex: 11 is a prime number because it is divisible by only 1 and 11. The numbers 0 and 1 are neither prime nor composite.

Here’s How You Do It Take out the number 1 because it is a special number

Here’s How You Do It Take out the number 1 because it is a special number

Here’s How You Do It Take out numbers that have a composite factor of 2

Here’s How You Do It Take out numbers that have a composite factor of 2

Here’s How You Do It Take out numbers that have a composite factor of 3

Here’s How You Do It Take out numbers that have a composite factor of 3

Here’s How You Do It Take out numbers that have a composite factor of 5

Here’s How You Do It Take out numbers that have a composite factor of 5

Here’s How You Do It Take out numbers that have a composite factor of 7

The PRIME Numbers! Take out numbers that have a composite factor of 7

Tell whether each number is prime or composite. Additional Example 2: Identifying Prime and Composite Numbers A. 23 divisible by 1, 23 prime B. 48 divisible by 1, 2, 3, 4, 6, 8, 12, 16, 24, 48. composite