## December 2011 Week 3 Post List

Hi everyone. Welcome to the pre-Christmas edition of the weekly summary of Math and Multimedia. Here are the list of posts for this week from my three blogs.

I. Math and Multimedia

II. GeoGebra Applet Central

III. School of Freebies

Announcement: Deadline of Submission for the Math and Multimedia Carnival is today. Please email kristi.grande@gmail.com for your submissions.

## Divisibility by 6

This is the fifth post in the Divisibility Rules Series.  In the previous posts, we have discussed divisibility by 2, 3, 4, 5 and 10. In this post, we discuss divisibility by 6.

First, we observe that all multiples of six (6, 12, 18, 24 …) are even. We are sure of this because any number multiplied by an even number is even.  Also, we can observe that  multiples of 6 are also divisible by 3: 6(1), 6(2), 6(3), 6(4) =   (2)(3)(1), (2)(3)(2), (2)(3)(3), (2)(3)(4),…. This, of course, follow from the fact that 6 is divisible by 3. Therefore, a number is divisible by 6 if it is divisible by 2 and it is divisible by 3.

In general, all multiples of 6 are in the form 6k, where k is any integer. But 6 is both divisible by 2 and 3. Therefore, a number is divisible by 6 if it is divisible by 2 and 3.