# Re: atomic

From: Bob Badour <bbadour_at_pei.sympatico.ca>

Date: Thu, 01 Nov 2007 13:23:22 -0300

Message-ID: <4729fd7d$0$14864$9a566e8b_at_news.aliant.net>

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

Date: Thu, 01 Nov 2007 13:23:22 -0300

Message-ID: <4729fd7d$0$14864$9a566e8b_at_news.aliant.net>

paul c wrote:

> Bob Badour wrote: >

*>> 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.**>>**>>**>> Shhhhh! You've ruined it! Now nobody will bother converting numbers to**>> base 9 to see if it actually works. Spoilsport!**>>**>>**>>> 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.**>>**>>**>> If the number is divisible by any factor of n-1, the sum of the digits**>> will be a multiple of that factor too. Thus, if one repeatedly sums**>> the digits of a hexadecimal number, one can tell very quickly whether**>> the number is divisible by 3, 5 or F.**>>**>> 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.*> > > Heh, personally, I prefer to think of all the numbers in my db as base > 10**64 or so with a floating decimal, even if there isn't a dbms that > supports that. Helps keep me from getting confused by more intricate > representations.

If so, shouldn't that be 10**1000000 ? Received on Thu Nov 01 2007 - 17:23:22 CET