Multiple ways to generate any number of nines (or any digit for that matter) via PHP

generateNines.php

<pre>
<?php

  //By @pkspencer
  function generateNines_One($numNines)
  {
    $result = 0;
    for ($i=0; $i < $numNines; $i++) {
      $result += pow(10, $i);
    }
    $result = $result * 9;
    return $result;
  }

  //By @collintbrown
  function generateNines_Two($numNines)
  {
    return pow(10, $numNines)-1;
  }

  //By @rjhilgefort
  function generateNines_Three($numNines)
  {
    return str_pad('', $numNines, "9");
  }

  print "||| Solution One |||\n";
  print "x=5:  " . generateNines_One(5) . "\n";
  print "x=10: " . generateNines_One(10) . "\n\n";

  print "||| Solution Two |||\n";
  print "x=5:  " . generateNines_Two(5) . "\n";
  print "x=10: " . generateNines_Two(10) . "\n\n";

  print "||| Solution Three |||\n";
  print "x=5:  " . generateNines_Three(5) . "\n";
  print "x=10: " . generateNines_Three(10) . "\n\n";


  /******* OUTPUT *************************************
  ||| Solution One |||
  x=5:  99999
  x=10: 9999999999

  ||| Solution Two |||
  x=5:  99999
  x=10: 9999999999

  ||| Solution Three |||
  x=5:  99999
  x=10: 9999999999
  ****************************************************/

?>
</pre>

Thanks for the contributions:

Solution One
https://twitter.com/pkspencer

Solution Two
https://twitter.com/collintbrown

Solution Three
https://twitter.com/rjhilgefort