Some useful php functions for receiving and returning various values from various inputs. Going from numbers to words and visa versa.

useful-math-functions.php

<?php

/*
 * This function turns a number into the ordinal word for the number
 *
 * Parameter : integer
 * Returns   : string
 */
function numToOrdinalWord($num) {
  $first_word = array('eth','first','second','third','fourth','fifth','sixth','seventh','eighth','ninth','tenth','eleventh','twelfth','thirteenth','fourteenth','fifteenth','sixteenth','seventeenth','eighteenth','nineteenth','twentieth');
  $second_word = array('','','twenty','thirty','forty','fifty', 'sixty', 'seventy', 'eighty', 'ninty');

  if($num <= 20) {
    return $first_word[$num];
  }

  $first_num = substr($num,-1,1);
  $second_num = substr($num,-2,1);

  return $string = str_replace('y-eth','ieth',$second_word[$second_num].'-'.$first_word[$first_num]);
}

/*
 * This function turns a number into the ordinal prefix for the number
 *
 * Parameter : integer
 * Returns   : string
 */
function numToOrdinalNumber($number) {
  $ends = array('th','st','nd','rd','th','th','th','th','th','th');
  if ((($number % 100) >= 11) && (($number%100) <= 13)) {
      return $number. 'th';
  } else {
      return $number. $ends[$number % 10];
  }
}

/*
 * This function turns a number into the word(s) for the number
 *
 * Parameter : integer
 * Returns   : string
 */
function convertNumberToWord($num = false) {
  $num = str_replace(array(',', ' '), '' , trim($num));
  if(! $num) {
      return false;
  }
  $num = (int) $num;
  $words = array();
  $list1 = array('', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven',
      'twelve', 'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'
  );
  $list2 = array('', 'ten', 'twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninety', 'hundred');
  $list3 = array('', 'thousand', 'million', 'billion', 'trillion', 'quadrillion', 'quintillion', 'sextillion', 'septillion',
      'octillion', 'nonillion', 'decillion', 'undecillion', 'duodecillion', 'tredecillion', 'quattuordecillion',
      'quindecillion', 'sexdecillion', 'septendecillion', 'octodecillion', 'novemdecillion', 'vigintillion'
  );
  $num_length = strlen($num);
  $levels = (int) (($num_length + 2) / 3);
  $max_length = $levels * 3;
  $num = substr('00' . $num, -$max_length);
  $num_levels = str_split($num, 3);
  for ($i = 0; $i < count($num_levels); $i++) {
      $levels--;
      $hundreds = (int) ($num_levels[$i] / 100);
      $hundreds = ($hundreds ? ' ' . $list1[$hundreds] . ' hundred' . ' ' : '');
      $tens = (int) ($num_levels[$i] % 100);
      $singles = '';
      if ( $tens < 20 ) {
          $tens = ($tens ? ' ' . $list1[$tens] . '' : '' );
      } else {
          $tens = (int)($tens / 10);
          $tens = ' ' . $list2[$tens] . ' ';
          $singles = (int) ($num_levels[$i] % 10);
          $singles = ' ' . $list1[$singles] . ' ';
      }
      $words[] = $hundreds . $tens . $singles . ( ( $levels && ( int ) ( $num_levels[$i] ) ) ? ' ' . $list3[$levels] . ' ' : '' );
  } //end for loop
  $commas = count($words);
  if ($commas > 1) {
      $commas = $commas - 1;
  }
  return implode(' ', $words);
}