# Re: atomic

From: Bob Badour <bbadour_at_pei.sympatico.ca>

Date: Thu, 01 Nov 2007 12:36:37 -0300

Message-ID: <4729f288$0$14877$9a566e8b_at_news.aliant.net>

> This is a joke, right? For radix n, n-1 has this interesting property.

Date: Thu, 01 Nov 2007 12:36:37 -0300

Message-ID: <4729f288$0$14877$9a566e8b_at_news.aliant.net>

David Cressey wrote:

> "Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message

*> news:4728f759$0$14832$9a566e8b_at_news.aliant.net...
**>
*

>>It's ironic you should mention base 9. It's a little-known fact that, if >>a number is evenly divisible by 8, the sum of the digits of the number >>in base 9 is also evenly divisible by 8. And if one repeats the process >>with that sum until the resulting sum has only one digit and if the >>original number was divisible by 8, the one remaining digit will be 8. >> >>It's like magic. So it's really ironic you should mention base 9 in >>particular.

*>*> This is a joke, right? For radix n, n-1 has this interesting property.

> Likewise, 9 has this fun property in decimals. Bookkeepers in the Bob

*> Chratchit era used a property much like this one for error detection in
**> manually managed numbers.
**>
**> If this were another person posting, I'd think it was simple oversight.
**> But you, BB, are likely to know exactly what I've just said.
*

Base 9 is actually a little less useful because it can only tell you if the number is divisible by 2, 4 or 8, and these are often relatively obvious in other bases in any case. Received on Thu Nov 01 2007 - 16:36:37 CET