Use this method on a positive integer less than one quadrillion and it will return it in english.

numbers_to_words.rb

class Fixnum
  def in_words
    first_twenty = { "0" => "Zero", "1" => "One", "2" => "Two", "3" => "Three", "4" => "Four", "5" => "Five", "6" => "Six", "7" => "Seven",
     "8" => "Eight", "9" => "Nine", "10" => "Ten", "11" => "Eleven", "12" => "Twelve", "13" => "Thirteen", "14" => "Fourteen", 
     "15" => "Fifteen", "16" => "Sixteen", "17" => "Seventeen", "18" => "eighteen", "19" => "Nineteen"  }
    tens = { "2" => "Twenty", "3" => "Thirty", "4" => "Fourty", "5" => "Fifty", "6" => "Sixty", "7" => "Seventy", "8" => "Eighty",
     "9" => "Ninety" }
    big_number = { 3 => "-Hundred and ", 4 => "-Thousand", 5 => "-Thousand", 6 => "-Thousand", 7 => "-Million", 8 => "-Million", 9 => "-Million", 10 => "-Billion", 11 => "-Billion", 12 => "-Billion",
      13 => "-Trillion", 14 => "-Trillion", 15 => "-Trillion"  }
    number_string = self.to_s
    big_num = big_number[number_string.length]
    if self < 20
      first_twenty[number_string]
    elsif self < 100
      tens[number_string[0]] + "-" + first_twenty[number_string[1]]
    elsif self < 1000
      if number_string[1].to_i == 1
        exception_1 = number_string[1] << number_string[2]
        number_string[0].to_i.in_words + big_num + exception_1.to_i.in_words
      elsif number_string[2].to_i == 0
        number_string[0].to_i.in_words + big_num + number_string[1].to_i.in_words
      else  
        number_string[0].to_i.in_words + big_num + number_string[1..2].to_i.in_words
      end
    elsif self < 10000
      number_string[0].to_i.in_words + big_num + " " + number_string[1..self].to_i.in_words
    elsif self < 100000
      number_string[0..1].to_i.in_words + big_num + " " + number_string[2..self].to_i.in_words
    elsif self < 1000000
      number_string[0..2].to_i.in_words + big_num + " " + number_string[3..self].to_i.in_words
    elsif self < 10000000
      number_string[0].to_i.in_words + big_num + " " + number_string[1..self].to_i.in_words
    elsif self < 100000000
      number_string[0..1].to_i.in_words + big_num + " " + number_string[2..self].to_i.in_words
    elsif self < 1000000000
      number_string[0..2].to_i.in_words + big_num + " " + number_string[3..self].to_i.in_words
    elsif self < 10000000000
      number_string[0].to_i.in_words + big_num + " " + number_string[1..self].to_i.in_words
    elsif self < 100000000000
      number_string[0..1].to_i.in_words + big_num + " " + number_string[2..self].to_i.in_words
    elsif self < 1000000000000
      number_string[0..2].to_i.in_words + big_num + " " + number_string[3..self].to_i.in_words
    elsif self < 10000000000000
      number_string[0].to_i.in_words + big_num + " " + number_string[1..self].to_i.in_words
    elsif self < 100000000000000
      number_string[0..1].to_i.in_words + big_num + " " + number_string[2..self].to_i.in_words
    elsif self < 1000000000000000
      number_string[0..2].to_i.in_words + big_num + " " + number_string[3..self].to_i.in_words
        
      
    end
  end
end


    #unit tests
puts "'#{0.in_words}' should be 'Zero'"
puts "'#{4.in_words}' should be 'Four'"
puts "'#{9.in_words}' should be 'Nine'"
puts "'#{13.in_words}' should be 'Thirteen'"
puts "'#{22.in_words}' should be 'Twenty-Two'"
puts "'#{37.in_words}' should be 'Thirty-Seven'"
puts "'#{137.in_words}' should be 'One-Hundred and Thirty-Seven'"
puts "'#{287.in_words}' should be 'Two-Hundred and Eighty-Seven'"
puts "'#{396.in_words}' should be 'Three-Hundred and Ninety-Six'"
puts "'#{420.in_words}' should be 'Four-Hundred and Twenty'"
puts "'#{511.in_words}' should be 'Five-Hundred and Eleven'"
puts "'#{613.in_words}' should be 'Six-Hundred and Thirteen'"
puts "'#{750.in_words}' should be 'Seven-Hundred and Fifty'"
puts "'#{819.in_words}' should be 'Eight-Hundred and Nineteen'"
puts "'#{999.in_words}' should be 'Nine-Hundred and Ninety-Nine'"
puts "'#{1248.in_words}' should be 'One-Thousand Two-Hundred and Fourty-Eight'"
puts "'#{14248.in_words}' should be 'Fourteen-Thousand Two-Hundred and Fourty-Eight'"
puts "'#{278248.in_words}' should be 'Two-Hundred and Seventy-Eight-Thousand Two-Hundred and Fourty-Eight'"
puts "'#{8748353.in_words}' should be 'Eight-Million Seven-Hundred and Fourty-Eight-Thousand Eight-Hundred and Fifty-Three'"
puts "'#{24874833.in_words}' should be 'Twenty-Four-Million Eight-Hundred and Seventy-Four-Thousand Eight-Hundred and Thirty-Three'"
puts "'#{193059395.in_words}' should be 'Nine-Hundred and Ninety-Nine'"
puts "'#{1948374629.in_words}' should be 'Nine-Hundred and Ninety-Nine'"
puts "'#{19385730926.in_words}' should be 'Nine-Hundred and Ninety-Nine'"
puts "'#{893059939209.in_words}' should be 'Nine-Hundred and Ninety-Nine'"
puts "'#{2782487483953.in_words}' should be 'Nine-Hundred and Ninety-Nine'"
puts "'#{27824487483953.in_words}' should be 'Nine-Hundred and Ninety-Nine'"
puts "'#{278584874839533.in_words}' should be 'Nine-Hundred and Ninety-Nine'"