9-6-12

Good evening!

In class this week, the following topics were covered:
-divisibility rules for the numbers 2, 3, 4, 5, 6, 9, and 10
-factor trees
-prime factorization
-finding the missing factor

We will have a test tomorrow (Friday, September 7th) covering the above topics. I encourage you to help your student commit the divisibility rules to memory over the next week.

Here they are:

Dividing by 2

1. All even numbers (numbers that end in 0,2,4,6, or 8) are divisible by 2

Dividing by 3

1. Add up all the digits in the number.
2. Find out what the sum is. If the sum is divisible by 3, so is the number. Example: 12123 (1+2+1+2+3=9) 9 is divisible by 3, therefore 12123 is too!

Dividing by 4

1. Box or circle the last two digits
2. Are the last two digits of your number divisible by 4?
3. If so, the number is too! Example: 358912 ends in 12 which is divisible by 4. Therefore, 358912 is divisible by 4

Divisible by 5

1. Numbers ending in a 5 or a 0 are always divisible by 5

Divisible by 6

1. If the number is divisible by both 2 and 3, then it is also divisible by 6

Divisible by 9

1. Almost the same rule as dividing by 3. Add up all the digits in the number.
2. Find out what the sum is. If the sum is divisible by 9, so is the number. Example: 43785 (4+3+7+8+5=27) 27 is divisible by 9. Therefore 43785 is too!

Divisible by 10

1. If the number ends in a 0, it is divisible by 10

Happy memorizing and studying!



Ms. Wheeler