Location: The Quad

The information about the Frosty Keypad acn be found by talking to Tangle Coalbox. This is summarized as:

Hint

I've got a few clues for you.

  1. One digit is repeated once.
  2. The code is a prime number.
  3. You can probably tell by looking at the keypad which buttons are used.

So looking at the picture of the keypad we can see that 1, 3 and 7 are the most smudged from use. This implies 3 number, but one is repeated once, so the code is 4 digits long and a prime number.

Kepad

I found a list of prime numbers up to 10,000 and put them into a small perl program:

#!/usr/bin/perl

use strict;
use English;

my $primes="2, [SNIPPED FOR CLARITY], 9973";

foreach my $prime ( split(", ", $primes)){
  my @digits = split("", $prime);

  if( $#digits == 3) {
    my $count_1 = 0;
    my $count_3 = 0;
    my $count_7 = 0;
    my $count_other = 0;
    foreach my $digit (@digits) {
      if( $digit == 1 ) {
        ++$count_1;
      } elsif ( $digit == 3 ) {
        ++$count_3;
      } elsif ( $digit == 7 ) {
        ++$count_7;
      } else {
        ++$count_other;
      }
    }
    next if( $count_other > 0 );
    next if( $count_1 > 2 || $count_3 > 2 ||$count_7 > 2 );
    next if( $count_1 == 0 || $count_3 == 0 ||$count_7 == 0 );
    print "$prime\n";
  }
}

The result was the following list:

1373

1733

3137

3371

7331

The answer was 7331.