Re: Why is 12345678, 85263147, etc. always divisible by 9?

On 19 Feb 2006 11:34:19 -0800, bill wrote:

Ignacio Larrosa Cañestro wrote:
En el mensaje:1140357815.354141.312390@xxxxxxxxxxxxxxxxxxxxxxxxxxxx,
TonyVarden <TonyVarden@xxxxxx> escribió:
You can arrange the digits from 1 to 8 in any combination & the
resulting number will always be divisible by 9.

ex:
12345678 / 9 = 1371742
85263147 / 9 = 9473683
etc.
Why?

Don't know the divisibility rule fby 9?

A number is divisible by 9 iif the sum of its digits (in base 10) is
multiple of 9.

But why? If the sum of the digits is a multiple of 7, the number is
not necessarily divisible by 7.

It is, if you are working in base 8.


--
Dave Seaman
U.S. Court of Appeals to review three issues
concerning case of Mumia Abu-Jamal.
<http://www.mumia2000.org/>
.

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