1. Learn to use divisibility rules. 4.1 Divisibility

2. Vocabulary divisible composite number prime number

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

4. 10,53615,99010 if the last digit is 0. 937119 if the sum of the digits is divisible by 9. 20486 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 4. 1393153 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

5. Division by 0 is undefined. Remember!

6. Additional Example 1A: Checking Divisibility Tell whether 462 is divisible by 2, 3, 4, and 5. 5 4 3 2 Not divisible So 462 is divisible by 2 and 3. The last digit, 2, is even. The sum of the digits is 4 + 6 + 2 = 12. 12 is divisible by 3. The last two digits form the number 62. 62 is not divisible by 4. Divisible Not divisible The last digit is 2.

7. Additional Example 1B: Checking Divisibility Tell whether 540 is divisible by 6, 9, and 10. 10 9 6 So 540 is divisible by 6, 9, and 10. The number is divisible by both 2 and 3. The sum of the digits is 5 + 4 + 0 = 9. 9 is divisible by 9. The last digit is 0. Divisible

8. 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.

9. 12345678910 11121314151617181920 21222324252627282930 31323334353637383940 41424344454647484950 51525354555657585960 61626364656667686970 71727374757677787980 81828384858687888990 919293949596979899100 Here’s How You Do It Take out the number 1 because it is a special number

10. 2345678910 11121314151617181920 21222324252627282930 31323334353637383940 41424344454647484950 51525354555657585960 61626364656667686970 71727374757677787980 81828384858687888990 919293949596979899100 Here’s How You Do It Take out the number 1 because it is a special number

11. 2345678910 11121314151617181920 21222324252627282930 31323334353637383940 41424344454647484950 51525354555657585960 61626364656667686970 71727374757677787980 81828384858687888990 919293949596979899100 Here’s How You Do It Take out numbers that have a composite factor of 2

12. 23579 1113151719 2123252729 3133353739 4143454749 5153555759 6163656769 7173757779 8183858789 9193959799 Here’s How You Do It Take out numbers that have a composite factor of 2

13. 23579 1113151719 2123252729 3133353739 4143454749 5153555759 6163656769 7173757779 8183858789 9193959799 Here’s How You Do It Take out numbers that have a composite factor of 3

14. 2357 11131719 232529 313537 41434749 535559 616567 71737779 838589 919597 Here’s How You Do It Take out numbers that have a composite factor of 3

15. 2357 11131719 232529 313537 41434749 535559 616567 71737779 838589 919597 Here’s How You Do It Take out numbers that have a composite factor of 5

16. 2357 11131719 2329 3137 41434749 5359 6167 71737779 8389 9197 Here’s How You Do It Take out numbers that have a composite factor of 5

17. 2357 11131719 2329 3137 41434749 5359 6167 71737779 8389 9197 Here’s How You Do It Take out numbers that have a composite factor of 7

18. 2357 11131719 2329 3137 414347 5359 6167 717379 8389 97 The PRIME Numbers! Take out numbers that have a composite factor of 7

19. 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