#!/usr/bin/perl
use v5.16;      # includes strict
use warnings;

my $output_file = "output.txt";

open(my $FH, ">", $output_file) or die "Can't open > $output_file: $!";

for (0 .. 3) {
    my $i = int(rand(10));
    say $i;
    say $FH $i;
}

close $FH;