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PHP : Human Readable Numbers

Originally published 4th December 2002

Ever wanted to display numbers in a human readable format? Then just use this simple routine. It uses simple recursion and a 'stepping' process to gradually work it's way through the supplied number.

	function readable_number($a){

		$bits_a = array("thousand", "million", "billion", "trillion",
		$bits_b = array("ten", "twenty", "thirty", "fourty", "fifty", 
			"sixty", "seventy", "eighty", "ninety");
		$bits_c = array("one", "two", "three", "four", "five", "six", 
			"seven", "eight", "nine", "ten", "eleven", "twelve", 
			"thirteen", "fourteen", "fifteen", "sixteen", "seventeen", 
			"eighteen", "nineteen");

		if ($a==0){return 'zero';}

		$out = ($a<0)?'minus ':'';

		$a = abs($a);
		for($i=count($bits_a); $i>0; $i--){
			$p = pow(1000, $i);
			if ($a > $p){
				$b = floor($a/$p);
				$a -= $p * $b;
				$out .= readable_number($b).' '.$bits_a[$i-1];
				$out .= (($a)?', ':'');
		if ($a > 100){
			$b = floor($a/100);
			$a -= 100 * $b;
			$out .= readable_number($b).' hundred'.(($a)?' and ':' ');
		if ($a >= 20){
			$b = floor($a/10);
			$a -= 10 * $b;	
			$out .= $bits_b[$b-1].' ';
		if ($a){
			$out .= $bits_c[$a-1];
		return $out;

Here's some sample output:

	8 = eight
	12 = twelve
	-27 = minus twenty seven
	186 = one hundred and eighty six
	1,234,567 = one million, two hundred and thirty four thousand, five hundred 
		and sixty seven

Note: American English speakers may find the use of 'and' confusing, as it's used in America as the decimal point delimiter, where as here we're using 'point'. Changing the code to be compatible with Americans is left as a (simple) exercise for the reader.