^

Divisibility rules for 3, 4, 6, 8 and 9

We briefly review the easy divisibility rules for 2, 5, 10, and 100. Then I explain in detail, and with examples, the divisibility test for 3 (add the digits; if the digit sum is divisible by 3, so is the number) and the similar test for 9. The rule for 4 says that if the last digits of the number are divisible by 4, then so is the number itself. The rule for 6 is that if a number is divisible by both 2 and 3, then it is divisible by 6. For 8, I use a version stating that if half of the number is divisible by 4, then the number itself is divisible by 8.

This math lesson is meant for 5th or 6th grade, when students study factors, divisibility, and prime numbers.

Back to 5th grade videos index

Back to the index of all videos

WAIT!

Receive my monthly collection of math tips & resources directly in your inbox — and get a FREE Math Mammoth book!

You can unsubscribe at any time.

Math Mammoth Tour

Confused about the different options? Take a virtual email tour around Math Mammoth! You'll receive:

An initial email to download your GIFT of over 400 free worksheets and sample pages from my books. Six other "TOURSTOP" emails that explain the important things and commonly asked questions concerning Math Mammoth curriculum. (Find out the differences between all these different-colored series!)

This way, you'll have time to digest the information over one or two weeks, plus an opportunity to ask me personally about the curriculum.
A monthly collection of math teaching tips & Math Mammoth updates (unsubscribe any time)

"Mini" Math Teaching Course

This is a little "virtual" 2-week course, where you will receive emails on important topics on teaching math, including:

- How to help a student who is behind
- Troubles with word problems
- Teaching multiplication tables
- Why fractions are so difficult
- The value of mistakes
- Should you use timed tests
- And more!

A GIFT of over 400 free worksheets and sample pages from my books right in the very beginning. A monthly collection of math teaching tips & Math Mammoth updates (unsubscribe any time)