<![CDATA[Help!]]>It says that "See the video for the explanation, but I have checked multiple times and I don't get why powers of ten have to do with the divisibility rule for 3 and 9. Can someone please help?
Thanks!
]]>https://forum.poshenloh.com/topic/705/helpRSS for NodeThu, 22 Feb 2024 04:00:41 GMTSun, 10 Jan 2021 18:41:09 GMT60<![CDATA[Reply to Help! on Mon, 11 Jan 2021 15:32:52 GMT]]>@neatlobster Please take a look at your other post where I answered your question. https://forum.poshenloh.com/topic/707/question-what-does-it-mean-by-then-the-value-of-a-digit-in-its-place-is-exactly-the-sum-you-get-when-you-add-up-these-stray-1-s
]]>https://forum.poshenloh.com/post/3916https://forum.poshenloh.com/post/3916Mon, 11 Jan 2021 15:32:52 GMT<![CDATA[Reply to Help! on Mon, 11 Jan 2021 15:20:38 GMT]]>I haven't taken the course, but to prove the divisibility of 9 rule, basically what you do is write out the number in base ten form, or just like: a_110^n+a_210^(n-1)...+a_n10^0. So, we can take this modulo 9 and we get a_1+a_2...+a_n. So if a_1+a_2...+a_n is divisible by 9, then a_110^n+a_210^(n-1)...+a_n10^0 is divisible and our proof is complete.

EDIT: The reason this has to do with powers of ten is because we write it out with powers of ten

]]>https://forum.poshenloh.com/post/3914https://forum.poshenloh.com/post/3914Mon, 11 Jan 2021 15:20:38 GMT<![CDATA[Reply to Help! on Mon, 11 Jan 2021 14:32:46 GMT]]>@energizedpanda
Hmm, We get 9, 99, 999, .... So they are all mutiples of nine. Ok, now what?
P.S
why isn't "9 is equal to 3^2" correct?
]]>https://forum.poshenloh.com/post/3912https://forum.poshenloh.com/post/3912Mon, 11 Jan 2021 14:32:46 GMT<![CDATA[Reply to Help! on Sun, 10 Jan 2021 19:06:28 GMT]]>@neatlobster Try to see a pattern on what happens when you subtract 1 from powers of 10. You'll find something neat. ;D
]]>https://forum.poshenloh.com/post/3903https://forum.poshenloh.com/post/3903Sun, 10 Jan 2021 19:06:28 GMT