20110823, 14:20  #1 
(loop (#_fork))
Feb 2006
Cambridge, England
2×3,191 Posts 
Where did that 37 come from
At a party yesterday, my friend Simon commented that it was silly to display baudrates in hex, since decimal 38400 comes out in hex as 0x9600 and causes confusion.
That is, 9600 is a number for which 'read as if it were in hex' and 'multiply by four' are the same operation. 154231124 is a number for which 'read as if it were in hex' and 'multiply by 37' are the same operation. Likewise 224321889 [41] 187605873 [35] and 17996800 [22]. multipliers I have observed are 4, 6, 10, 16, 22, 25, 35, 37, 40, 41 (twice! 224321889 and 789458685), 42, 56, 61 (1365665301), 64, 65 (3502669923), 66 (1067455668), 67 (4251168226) ... this is an unnatural set of numbers but I suppose readasifitwereinhex is an unnatural operation. of course 11702482 [25] implies 117024820 [40] and 1170248200 [64] 187605873 [35] implies 1876058730 [56] Last fiddled with by fivemack on 20110824 at 18:10 
20110823, 20:20  #2  
Bamboozled!
"πΊππ·π·π"
May 2003
Down not across
2^{5}·331 Posts 
Quote:
(Yes, the old ones are the best.) Paul 31 OCT == 25 DEC 

20110823, 20:38  #3  
"Forget I exist"
Jul 2009
Dumbassville
2^{6}×131 Posts 
Quote:


20110824, 02:27  #4 
Aug 2006
13526_{8} Posts 

20110824, 19:36  #5 
"Forget I exist"
Jul 2009
Dumbassville
2^{6}·131 Posts 

20110824, 22:27  #6 
(loop (#_fork))
Feb 2006
Cambridge, England
2·3,191 Posts 
I've taken this in C++ code to about 2.5e12 for several bases, so probably there's little point writing very much pari. The smallest workingexample for base 11 is amusingly enormous (it's a tripling). Next interesting question is whether there are better search techniques than just counting.
You're looking for a short vector in the integer lattice perpendicular to some other vector, but I'm not sure how you encode 'nonnegative' for lattice problems; might well be able to do dynamic programming and get an answer for any given multiplier much more quickly than just counting. 
20110829, 06:01  #7  
May 2007
Kansas; USA
13^{2}·61 Posts 
Quote:
The problem posed by fivemack is a very interesting one. The question is: Did he really hear such a problem at a party? :) Last fiddled with by gd_barnes on 20110829 at 06:07 

20110829, 06:05  #8 
Romulan Interpreter
Jun 2011
Thailand
5^{2}×7×53 Posts 
that's 31 (octal) is 25 (decimal), a very old joke. But the problem is quite interesting, and I would also like to read some math behind. I stucked my ears into it, but without any relevant result.

20110829, 08:16  #9 
Mar 2006
Germany
2×1,439 Posts 
It's like:
"There are 10 kinds of people in the world β those who understand binary and those who don't." 
20110829, 15:50  #10  
Tribal Bullet
Oct 2004
2×3×19×31 Posts 
Quote:
I also wonder if the best one can do involves techniques that look like the branchandbound techniques from integer programming. 

20110829, 22:30  #11  
May 2007
Kansas; USA
24105_{8} Posts 
Quote:
I think the English phrase that you are looking for is "I put my head to it". :) That's funny. I had not heard either one of these before. 
