#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my @account = qw( 96329XY 7776fc 334457yg 2233oop 000001 8877666b);
my @file =  qw(8877666b.txt 2233oop.txt 334457yg.txt 7776fc.txt 96329X
+Y_K.txt);

my $ac_re = join '|', grep /^\d+/, @account;

print join "\n", grep /$ac_re/, @file;
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Just a (nother) thought :-)