Divisibility Tests for 2, 3, 5, 7 and 11

Video by Julie Harland http://yourmathgal.com This shows you the divisibility tests for 2, 3, 5, 7, and 11, so you can tell if those numbers are factors of a given number or not without dividing.

Category:

Education

Tags:

• divide
• divisibility
• tests
• arithmetic

[oiveiea9]

for 11

if its 8 digits how?

like:541292039

i onli hv 1 day left to answr dis

[videosbyjulieharland]

@oiveiea9: If it is more than 3 digits, add every other digit. Then add the other digits. Then subtract those 2 numbers. If it is 0, 11 or 22, it's divisible by 11. So, try 45981032. Add every other digit: 4+9+1+3=17 Now add the other digits (every other digit starting with the 2nd digit 5): 5+8+0+2=15. Now subtract: 17 - 15 =2. That's not 0 or 11 or 22, so it's not divisible by 11. Works no matter how many digits.

[lilo086]

what happens if you have a problem like this;

What is the smallest counting number divisible by 3, 9, 11, 15, and 45?

[videosbyjulieharland]

I posted 3 videos addressing your question. The smallest counting number divisible by 3, 9, 11, 15, and 45 is the same as asking for the least common multiple (LCM) of 3, 9, 11, 15, and 45. I show several ways to do this. All of my videos are organized on my website, or search LCM on my youtube site. On my website, these are listed under my math videos, then arithmetic, then LCM.

[videosbyjulieharland]

@lilo086 Youtube preventing me from posting my website and the links to the youtube videos in this reply, and your youtube site prevented me from sending you a message or making a comment on your site, so I hope you check back and figure this out. It's not too hard once you know how to find the LCM.

[augustbuckne717]

This video is popular on Kiribati

[ManiKevin]

thanks, this helped

[Myrslokstok]

Best video thanks!

[KCAASE]

Thank you and everything clearly explained with introduction, teaching, and a closure. I wish upon the stars that there are more math teachers as you out there, otherwise people will just hate math because those so-called math teachers can't explain anything.

[oiveiea9]

for 11

if it is 7 digits how to do it like :

4926549

[arpitsavenger]

@lilo086 @lilo086

hi arpit here :

find the lcm(least common factor...) of all nos. and the LCM is your answer

[arpitsavenger]

@lilo086

hi arpit here :

find the lcm(least common factor...) of all nos. and the LCM is your answer