$s = '1 23 456 789 0123 456 2 23 456 789 0123 456';

push @results, ("This looks like a word: $1") while $s =~ /((?:\b\d{1,2}\s+)+\b\d{3,})/g;
print "$_\n" for @results;

# Prints:
# This looks like a word: 1 23 456
# This looks like a word: 2 23 456