use strict;
use warnings;

my @strings = (
    'string that I need to gather the common base from: number 1 and some other junk in it',
    'string that I need to gather the common base from: number 2 and some other junk in it',
    'string that I need to gather the common base number 4 and some other junk in it',
    'string that I need to gather the common base from: number 3 and some other junk in it',
);
my $common = $strings[0];

for my $str (@strings[1 .. $#strings]) {
    ($common ^ $str) =~ m/^\0*/;
    $common = substr $str, 0, $+[0] if $+[0] < length $common;
}

print "'$common'";

##</code><code>##

'string that I need to gather the common base '