use strict;
use warnings;

my $variable = join("", <DATA>);

my @num = qw|zero one two three four five six seven eight nine|;

$variable =~ s/(\d)/$num[$1]/g;
print  "$variable";
__DATA__
This is 1 great time 2 have a 3 way 4some.
When 5 and 6 together make 11.
Some 8 or 9 of us will see that.