Kentucky Lottery Pick 3 Expected Payout

The expected payouts for the Kentucky Lottery Pick 3 game have an interesting idiosyncrasy. Playing the special “Straight Box” play pays out better than a separate 50¢ straight and 50¢ box play.

All other plays average 60¢ per dollar played, but the straight box seems to be 65¢ and 70¢, depending on the numbers played. Maybe my spreadsheet is wrong somewhere in here:

Entropy of iPhone headphone cables (an excuse to experiment with WP-LaTeX)

Why is it that iPhone earbuds seem to tangle with so many more hopeless tangles than any other cables? $displaystyle frac{dS_{iPhoneCable}}{dt} gg frac{dS_{genericCables}}{dt}$

Of course, this whole exercise was an excuse to play with LaTeX and the WP-LaTeX plugin.

I also managed to find a nice LaTeX cheat sheet in the process.

I just found an awesome site describing some of the features in Google while looking for info on Google Calculator:  Google Guide

My first find was the Quick Reference: Google Calculator (Cheat Sheet).

I like this tip from Google Guide solutions to Calculator problems:

Compute the probability of your winning the lottery if you buy 1,000 tickets each bearing five distinct independently randomly chosen integers between 1 and 99.

The following answer was contributed by Nelson Blachman (Nancy’s father).

You might try [ 1 – (1 – 1/(99 choose 5))^1000 ], but this is well approximated by [ 1000/(99 choose 5) ], which is roughly 0.00001 . If each ticket costs \$1, the prize had better be at least \$100 million to be fair to you — and higher if you might have to share the prize with other winners.

While I was on that train of thought, I found the Lottery Mathematics entry on Wikipedia.

Also…  I've always wanted to figure out the probability calculation for various poker hands.

Optimized prime number generator

Same specs as previous system, 8 hours to find all primes to ULONG_MAX.

#include <stdio.h>
#include <malloc.h>
#include <limits.h>
#include <math.h>

{
unsigned long number;
};

int main(int argc, char **argv)
{
unsigned long divisor, max_divisor, prime_test;
unsigned long max_prime_to_store;

first->number = 2L;
first->next = NULL;
last = first;
printf("%lun", 2L);

max_prime_to_store = 1L + sqrt(ULONG_MAX);

for(prime_test = 3L; prime_test < ULONG_MAX; prime_test+=2L)
{
max_divisor=1L+sqrt(prime_test);
for(current = first; current && current->number <= max_divisor; current = current->next)
{
if(prime_test % current->number == 0)
{
break;
}
}
if(!current || current->number > max_divisor)
{
if(prime_test <= max_prime_to_store)
{
last = last->next;
last->next = NULL;
last->number = prime_test;
}
printf("%lun", prime_test);
}
}
return 0;
}

I miss C programming. Program to find prime numbers

Uses unsigned long long, goes up to ULONG_LONG_MAX.

Intel Core Duo 2 processor, running Cygwin on Windows XP, and compiled using gcc 3.4.4. Stops at first million results due to time. Can reasonably get to 10 million, if you’re willing to wait.

#include <stdio.h>
#include <math.h>
#include <limits.h>

int main(int argc, char **argv)
{
unsigned long long divisor, max_divisor, prime_test;
int break_time = 0;

printf("%llun", 2LL);
for(prime_test = 3LL; prime_test < ULONG_LONG_MAX; prime_test+=2LL)
{
max_divisor=1LL+sqrt(prime_test);
for(divisor=3LL;divisor <= max_divisor; divisor+=2LL)
{
if(prime_test % divisor == 0)
{
break;
}
}
if(divisor >= max_divisor)
{
printf("%llun", prime_test);
}
else
{
continue;
}
break_time++;
if(break_time == 999999)
{
break;
}
}
return 0;
}