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A Little NUmber Curiosity

Posted: Fri Apr 30, 2010 12:11 pm
by DrDave
Recently, I was doing some number crunching that involved 9 and multiples thereof. Just for fun, look at the digits for the INVERSE of each of these numbers. The "special properties" (whatever that might mean) of 9 have been studied and used since ancient times.

In the numbers below, they mostly show insertion of zeros. But the set begining with 81 runs a bit differently by inserting various digits. And it appears 81*9 =729 contiunes with the insertion of digits. I didn't pursue this one further.

I'm sure those of you that are pattern finders will see also that the sum of the digits reduce to 9.

Also, why don't ALL numbers that reduce to 9 give these "unusual" sequences? For example, 27 doesn't produce a very "pleasing" sequences of digits.

9, 99, 999, 9999, ...

18, 1818, 181818, ...

45, 4545, 454545, ...

36, 3636, 363636, ...

81, 8181, 818181, 81818181, ...

108, 108108, 108108108, ...

81*9 = 729

DrDave

Re: A Little NUmber Curiosity

Posted: Sat May 01, 2010 7:58 am
by cormullion
I think there's a book about number 9. 9 is a bit odd in my view.

Re: A Little NUmber Curiosity

Posted: Sat May 01, 2010 4:07 pm
by DrDave
cormullion wrote: 9 is a bit odd in my view.
You are so right. And it's also a little square.

Re: A Little NUmber Curiosity

Posted: Sat May 01, 2010 10:35 pm
by Kazimir Majorinc
When you speak about problems with 27, that means that 1/27 doesn't make nice output, right?

Re: A Little NUmber Curiosity

Posted: Tue May 04, 2010 12:50 pm
by DrDave
Kazimir Majorinc wrote:When you speak about problems with 27, that means that 1/27 doesn't make nice output, right?
Essentially, yes. When you compare the inverse of 27, 27227, 27272, etc. with any of the others that I listed above, it doesn't seem to be inserting either zeros or other digits as the above numbers do.