I took a course in probability a few years ago and have not made my fortune in the casino yet. This program can help to count cards in single-deck blackjack and determine the odds of going bust based on your hand. The interface is quite crude :)

This is certainly not as cool as a system which is easy to memorize, but I think it's kindof cool. Here goes:

#!/usr/bin/perl

##
#
# Card Counter :  This is a basic single-deck blackjack card counter. 
+ It calculates the probability
#                 of going bust based on the cards which have been pla
+yed.  I'd love to generalize
#                 this some more as there are 5^12 possible states for
+ the deck when playing
#                 from a single deck, and this is too much for me to m
+emorize.
#
#                 Rohit Kumar Mehta
#
#                 2003.07.17
#
##

use strict;

my @deck;
my $num;

sub showdeckstats {
  my @deck=@_;
  my $totalcards=0;
  my @prob;

  print "\t\t+---+---+---+---+---+---+---+---+---+---+---+---+---+\n";
  print "card key\t| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10| 11| 1
+2|\n";
  print "\t\t+---+---+---+---+---+---+---+---+---+---+---+---+---+\n";
  print "card value\t| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10| J | Q | K |
+ A |\n";
  print "\t\t+===+===+===+===+===+===+===+===+===+===+===+===+===+\n";

  print "# in deck\t";
  for (my $count=0; $count<=12; $count++) {
    print "| $deck[$count] ";
    $totalcards += $deck[$count];
  }
  print "|\n\t\t+---+---+---+---+---+---+---+---+---+---+---+---+---+\
+n";
  print "\n\t\t\t+----+----+----+----+----+----+----+----+----+\n";
  print "value of your hand\t| 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 |
+ 20 |\n";
  print "\t\t\t+====+====+====+====+====+====+====+====+====+\n";
  print "prob bust next hit\t|";
  for (my $val=12; $val<21; $val++) {
    my $bust=0;
    my $nobust=0;

    for (my $card=0; $card<=12; $card++) {
      my $cardval;
      if ($card == 12) { $cardval=1; }
      elsif ($card >7) { $cardval=10; }
      else { $cardval = $card +2 }
      if ( ($val + $cardval) > 21 ) { $bust=$bust+$deck[$card]; }
      else { $nobust=$nobust+$deck[$card]; }
    }
    my $prob;
    $prob = $bust/($bust+$nobust);
    printf ("%1.2f|",$prob);
  }
  print "\n\t\t\t+----+----+----+----+----+----+----+----+----+\n";


}

#####
#
# initialize cards
#
#####

for (my $card = 0; $card <=12; $card++) {
  $deck[$card]=4;
}

while (1) {
showdeckstats(@deck);
print "\nenter the key number of the card you wish to subtract: ";
$num=<stdin>;
chomp $num;
$deck[$num]--;
}
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