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

I've got a few clues for you.

- One digit is repeated once.
- The code is a prime number.
- 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.

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.