Number in Words

numbers_in_words.rb

VALUES = { 1000000000000 => 'trillion ', 1000000000 => 'billion ', 1000000 => 'million ', 1000 => 'thousand ', 1 => '' }
TENS = ['', '', 'twenty ', 'thirty ', 'forty ', 'fifty ', 'sixty ', 'seventy ', 'eighty ', 'ninety ']
ONES = ['', 'one ', 'two ', 'three ', 'four ', 'five ', 'six ', 'seven ', 'eight ', 'nine ']
TEENS = ['ten ', 'eleven ', 'twelve ', 'thirteen ', 'fourteen ', 'fifteen ', 'sixteen ', 'seventeen ', 'eighteen ', 'nineteen ']

def to_word(number)
  power = 1000**(Math.log10(number).floor / 3)
  to_write = number / power
  number_as_word = get_hundreds(to_write) + get_tens(to_write) + get_ones(to_write) + VALUES[power]
  number_as_word << to_word(number % power) unless number % power == 0
  number_as_word.chomp
end

def get_hundreds(number)
  hundreds = number / 100
  hundreds > 0 ? ONES[hundreds] + 'hundred ' : ''
end

def get_tens(number)
  tens = number % 100 / 10
  if tens > 0
    tens == 1 ? TEENS[number % 100 - 10] : TENS[tens]
  else
    ''
  end
end

def get_ones(number)
  ones = number % 10
  (number % 100 / 10) != 1 ? ONES[ones] : ''
end

while number = gets.chomp
  break if number == ''
  puts to_word(number.to_i)
end