Function to convert a number to text

convertNumToString.php

public static function convertNumToString($number, $limit = 999999999999) {
  if (($number < 0) || ($number > $limit)) {
		return $number;
	}

	if ($number == 0) {
		return "zero";
	}

	$Tn = floor($number / 1000000000);  /* Trillions (tera) */
	$number -= $Tn * 1000000000;
	$Gn = floor($number / 1000000);  /* Millions (giga) */
	$number -= $Gn * 1000000;
	$kn = floor($number / 1000);	 /* Thousands (kilo) */
	$number -= $kn * 1000;
	$Hn = floor($number / 100);	  /* Hundreds (hecto) */
	$number -= $Hn * 100;
	$Dn = floor($number / 10);	   /* Tens (deca) */
	$n = $number % 10;			   /* Ones */

	$string = "";

	if ($Tn) {
		$string .= self::convertNumToString($Tn) .' Trillion';
	}

	if ($Gn) {
		$string .= self::convertNumToString($Gn) .' Million';
	}

	if ($kn) {
		$string .= ( empty($string) ?'' :' ') .
				self::convertNumToString($kn) .' Thousand';
	}

	if ($Hn) {
		$string .= ( empty($string) ?'' :' ') .
				self::convertNumToString($Hn) .' Hundred';
	}

	$ones = array('','One','Two','Three','Four','Five','Six',
		'Seven','Eight','Nine','Ten','Eleven','Twelve','Thirteen',
		'Fourteen','Fifteen','Sixteen','Seventeen','Eighteen',
		'Nineteen');
	$tens = array('','','Twenty','Thirty','Forty','Fifty','Sixty',
		'Seventy','Eighty','Ninety');

	if ($Dn || $n) {
		if (!empty($string)) {
			$string .=' and ';
		}

		if ($Dn < 2) {
			$string .= $ones[$Dn * 10 + $n];
		} else {
			$string .= $tens[$Dn];

			if ($n) {
				$string .= ' ' . $ones[$n];
			}
		}
	}

	return $string;
}