numbers_as_words.rb

UNITS = Hash[(1..9).zip %w(um dois tres quatro cinco seis sete oito nove)]
SPECIAL = Hash[(11..19).zip %w(onze doze treze quatorze quinze dezesseis dezessete dezoito dezenove)]
DOZENS = Hash[(1..9).zip %w(dez vinte trinta quarenta cinquenta sessenta setenta oitenta noventa)]

def to_words(number)
  return SPECIAL[number] if number.between?(11, 19)
  dozens, units = number.divmod(10)
  [DOZENS[dozens], UNITS[units]].compact.join(' e ')
end

# main program

(1..99).each do |n|
  puts to_words(n)
end