Download Module 2 lesson 17.notebook

Module 2 lesson 17.notebook
November 19, 2015
Thursday, November 19 2015
Aim: Divisibility tests for 3 and 9
Module 2/lesson 17
Opening Exercise
Discussion: Divisibility rules for:
2 ­ if its last digit is 0, 2, 4, 6 or 8
4 ­ last two digits are a number divisible by 4
5 ­ if its last digit is 0 or 5
8 ­ if its last three digits are a number divisible by 8
10­ if its last digit is 0
**What do the numbers 12, 18, 30, 66 and 93 have in common?
Rule for 3: if the sum of the digits is divisible by 3, then the number is divisible by 3
312 = 1 + 2 + 3 Rule for 9: if the sum of the digits is divisible by 9, then the number is divisible by 9.
Example 1:
Example 2:
.
Exercises:
1.
2.
3.
Summary:
*If the sum of the digits is divisible by 3, the entire number is divisible by 3.
*If the sum of the digits is divisible by 9, the entire number is divisible by 9.
**If a number is divisible by 9, the number is also divisible by 3.
1