code: public static function PERMUT($numObjs, $numInSet)
      {
          $numObjs = Functions::flattenSingleValue($numObjs);
          $numInSet = Functions::flattenSingleValue($numInSet);
  
          if ((is_numeric($numObjs)) && (is_numeric($numInSet))) {
              $numInSet = floor($numInSet);
              if ($numObjs < $numInSet) {
                  return Functions::NAN();
              }
  
              return round(MathTrig::FACT($numObjs) / MathTrig::FACT($numObjs - $numInSet));
          }
  
          return Functions::VALUE();
      }
docs: PERMUT.
  
  Returns the number of permutations for a given number of objects that can be
  selected from number objects. A permutation is any set or subset of objects or
  events where internal order is significant. Permutations are different from
  combinations, for which the internal order is not significant. Use this function
  for lottery-style probability calculations.
  
  @param int $numObjs Number of different objects
  @param int $numInSet Number of objects in each permutation
  
  @return int Number of permutations