require 'rubygems'
require 'br/cnpj'

BR::CNPJ.valid? '00000000000191'
 #> true

BR::CNPJ.valid? 191
 #> true

BR::CNPJ.valid? 192
 #> false

radix = 0
filial = 1
BR::CNPJ.new(radix, filial).to_s
 #> '00000000000191'

BR::CNPJ.new(191).valid?
 #> true

BR::CNPJ.new(1234567891011).valid?
 #> false

BR::CNPJ.format(191)
 #> '00.000.000/0001-91'

BR::CNPJ.unformat('00.000.000/0001-91')
 #> '00000000000191'