if ($totalmass != 0){@wtPercent = map{$_ / $totalmass}@wtPureAmt}else{$statustext = "You need to give me numbers!"};

##</code><code>##

if ($totalmass != 0){ 
	foreach (0 .. $#wtPercent) {
		$wtPercent[$_] = ($wtPureAmt[$_] / $totalmass); 
	}
} else {
	$statustext = "You need to give me numbers!"
};