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Free powerpoint to teach the topics of Divisibility to elementary school kids aspiring to compete in math contests such as the NLMC and Math Kangaroo

- 1. Topic 4. Divisibility WEEK 4. JUL.26
- 7. Definition of Divisibility Divisibility refers to a number's quality of being evenly divided by another number, without a remainder left over. For example: 63 ÷ 7 = 9 50 ÷ 10 = 5 Non examples: 79 ÷ 7 = 11 R2 39 ÷ 9 = 4 R3
- 8. Why should you learn divisibility? Divisibility rules of whole numbers are very useful because they help us to quickly determine if a number can be divided by single digit numbers and 10 without doing long division. This is especially useful when the numbers are large.
- 9. Divisibility Rule for 2 All even numbers are divisible by 2. So, all numbers ending in 0,2,4,6 or 8 can be divided by 2. Example: 34,290 Is 1827 divisible by 2?
- 10. Divisibility Rule for 3 Add up all the digits in the number to find out what the sum is. If the sum can be divided by 3, the whole number can be. Example: 333 (3 + 3 + 3 = 9) and 9 is divisible by 3, so the whole number is! Is 3561 divisible by 3?
- 11. Divisibility Rule for 4 Are the last two digits in your number divisible by 4? If so, the whole number is too! Example: 728 (28 is divisible by 4) so the whole number is! Is 4876 divisible by 4?
- 12. Divisibility Rule for 5 Any number ending in a 5 or a 0 are always divisible by 5. Example: 1,224,325 Is 0 divisible by 5?
- 13. Divisibility Rule for 6 If the number is divisible by 2 and 3 it is divisible by 6. Example: 612 (it is an even number, so it is divisible by 2) and 6 + 2 + 1 = 9 and 9 is divisible by 3. Is 108 divisible by 6?
- 14. Divisibility Rule for 7 If you double the last digit and subtract it from the rest of the number and the answer is: 0 OR divisible by 7. Example: 672 (Double 2 is 4, then 67-4=63, and 63 is divisible by 7.) Is 2457 divisible by 7?
- 15. Divisibility Rule for 8 If the last 3 digits are divisible by 8. Example: 1824 (824 is divisible by 8) Is 4120 divisible by 8?
- 16. Divisibility Rule for 9 If the sum of the digits is divisible by 9, then the whole number is divisible by 9. Example: 999 (9 + 9 + 9 = 27) and 27 is divisible by 9, so the whole number is. Is 5364 divisible by 9?
- 17. Practice Problem Let’s try filling out this chart using divisibility rules
- 18. Answer Yes No No No Yes No No Yes No Yes No Yes No No Yes Yes No Yes No No Yes Yes No Yes Yes Yes No Yes No Yes Yes No No No No No No No Yes Yes Yes No Yes Yes No Yes Yes No Yes Yes No No Yes No Yes No Yes Yes No No Yes No No Yes No No No No No Let’s try filling out this chart using divisibility rules
- 19. Divisibility Rule for 10 If a number ends in a 0, it is divisible by 10. Also if a number is divisible by both 2 and 5, it is divisible by 10 Example: 30, 55800, 67920
- 20. Review Problem: Which of the following numbers is divisible by 3? a)51412 b)86221 c)63693
- 21. Answer Which of the following numbers is divisible by 3? c) 63693
- 22. Review Problem: Which of the following numbers is divisible by 6? a)39052 b)80148 c)52335
- 23. Answer Which of the following numbers is divisible by 6? b) 80148
- 24. Practice Problem: There are 1,728 fish in a hatchery, which are divided evenly among the ponds. How many ponds could there be at the hatchery? a)10 b)4 c)5
- 25. Answer There are 1,728 fish in a hatchery, which are divided evenly among the ponds. How many ponds could there be at the hatchery? b) 4
- 26. Practice Problem Is 41295 divisible by 15?
- 27. Answer If we can verify that 41295 is divisible by both 3 and 5, then it is divisible by 15. Sum of the digits in 41295 : 4 + 1 + 2 + 9 + 5 = 21 Because 21 is a multiple of 3, 41295 is divisible by 3. In 41295, the digit in one's place is 5. Therefore, 41295 is divisible by 5. Now, it is clear that 41295 is divisible by both 3 and 5. So, 41295 is divisible by 15.
- 28. Practice Problem
- 29. Answer
- 31. Answer:
- 32. Time for handouts! Take the handouts that you printed out at home and using the concepts that we learned today, start working on them. If you don’t finish that’s okay, you can finish it at home.