Installation

gem 'numbers_in_words'

require 'numbers_in_words'
require 'numbers_in_words/duck_punch' #see why later

This project was created for a test for a job interview. I haven't really used it myself, but I saw it mentioned somewhere so I thought I'd tidy it up a bit.

I'm going to hopefully preempt some support queries by predicting this will happen:

You've got one of:

NoMethodError: undefined method `in_words' for 123:Fixnum
NoMethodError: undefined method `in_numbers' for "123":String

Here's why

Previous versions of this gem duckpunched Fixnum and String with a whole bunch of methods. This gem will now only add methods if you specifically tell it to with:

require 'numbers_in_words'
require 'numbers_in_words/duck_punch'

Plus it now only adds a single #in_words method to Numeric and an #in_numbers method to String instead of a whole bunch of them.

Usage

require 'numbers_in_words'
require 'numbers_in_words/duck_punch'
112.in_words
#=> one hundred and twelve

"one googol".in_numbers
#=>10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

"Seventy million, five-hundred and fifty six thousand point eight nine three".in_numbers
#=> 70556000.893

---

Whilst creating this project I realized that in English:

• Numbers are grouped in groups of threes
• Numbers less than 1,000 are grouped by hundreds and then by tens
• There are specific rules for when we put an "and" in between numbers

It makes sense to manage the numbers by these groups, so I created a method groups_of which will split any integer into groups of a certain size. It returns a hash with the power of ten as the key and the multiplier as the value. E.g:

31245.groups_of(3)
#=> {0=>245,3=>31} #i.e. 31 thousands, and 245 ones

245.group_of(2)
#=> {0=>45,2=>2}    #i.e. 2 hundreds, and 45 ones

(In Japanese numbers are grouped in groups of 4, so it makes sense to try and separate the language related stuff from the number grouping related stuff)

Example of usage:

245.group_words(2,"English") do |power, name, digits|
  puts "#{digits}*10^#{power} #{digits} #{name}s"
end


2  * 10^2 =  2 hundreds
45 * 10^0 = 45 ones

Future plans

• Handle complex numbers
• Option for outputting punctuation
• Reject invalid numbers
• Support for other languages