my @numbers4 = $text =~ /\b \d{4} \b/gx;
foreach $unit4 (@numbers4) {
$text =~ s/$unit4/\<a href=\"unit=$unit4\"\>\<b\>$unit4\<\/b\>\<\/a\>/i;
}

# look for 3 digit numbers and make link to Resident Info card.
my @numbers3 = $text =~ /\b \d{3} \b/gx;
foreach $unit3 (@numbers3) {
$text =~ s/$unit3/\<a href=\"?unit=$unit3\"\><b\>$unit3<\/b\>\<\/a\>/i;
}