module ActionView::Helpers::NumberHelper

number_to_human(0.34, :units => :distance) # => "34 centimeters"
number_to_human(1, :units => :distance) # => "1 meter"
number_to_human(343, :units => :distance, :precision => 1) # => "300 meters"
number_to_human(54393498000, :units => :distance) # => "54.4 gazilion-distance"
number_to_human(54393498, :units => :distance) # => "54400 kilometers"
number_to_human(543934, :units => :distance) # => "544 kilometers"

Then you could do:

billion: "gazilion-distance"
other: "kilometers"
one: "kilometer"
thousand:
other: "meters"
one: "meter"
unit:
other: "centimeters"
one: "centimeter"
centi:
distance:
If in your I18n locale you have:

number_to_human(500000, :units => {:unit => "ml", :thousand => "lt"}) # => "500 lt"
You can also use your own custom unit quantifiers:

==== Custom Unit Quantifiers

number_to_human(500000000, :precision=>5) # => "500 Million"
number_to_human(12345012345, :significant_digits => 6) # => "12.345 Billion"
:strip_insignificant_zeros to +false+ to change that):
Unsignificant zeros after the decimal separator are stripped out by default (set

:significant => false) # => "1,2 Million"
:separator => ',',
number_to_human(1234567, :precision => 1,
:significant => false) # => "1.2346 Million"
number_to_human(1234567, :precision => 4,
number_to_human(489939, :precision => 4) # => "489.9 Thousand"
number_to_human(489939, :precision => 2) # => "490 Thousand"
number_to_human(1234567890123456789) # => "1230 Quadrillion"
number_to_human(1234567890123456) # => "1.23 Quadrillion"
number_to_human(1234567890123) # => "1.23 Trillion"
number_to_human(1234567890) # => "1.23 Billion"
number_to_human(1234567) # => "1.23 Million"
number_to_human(12345) # => "12.3 Thousand"
number_to_human(1234) # => "1.23 Thousand"
number_to_human(123) # => "123"
==== Examples

%n The number
%u The quantifier (ex.: 'thousand')

* :format - Sets the format of the output string (defaults to "%n %u"). The field types are:
* *fractionals*: :deci, :centi, :mili, :micro, :nano, :pico, :femto
* *integers*: :unit, :ten, :hundred, :thousand, :million, :billion, :trillion, :quadrillion
* :units - A Hash of unit quantifier names. Or a string containing an i18n scope where to find this hash. It might have the following keys:
* :strip_insignificant_zeros - If +true+ removes insignificant zeros after the decimal separator (defaults to +true+)
* :delimiter - Sets the thousands delimiter (defaults to "").
* :separator - Sets the separator between the fractional and integer digits (defaults to ".").
* :significant - If +true+, precision will be the # of significant_digits. If +false+, the # of fractional digits (defaults to +true+)
* :precision - Sets the precision of the number (defaults to 3).
* :locale - Sets the locale to be used for formatting (defaults to current locale).
==== Options

a wide range of unit quantifiers, even fractional ones (centi, deci, mili, etc).
(eg.: 1500 becomes "1.5 kilometers", 0.150 becomes "150 mililiters", etc). You may define
You can also define you own unit-quantifier names if you want to use other decimal units

See number_to_human_size if you want to print a file size.

can get very large (and too hard to read).
(eg.: 1200000000 becomes "1.2 Billion"). This is useful for numbers that
Pretty prints (formats and approximates) a number in a way it is more readable by humans

def number_to_human(number, options = {})
  options.symbolize_keys!
  number = begin
    Float(number)
  rescue ArgumentError, TypeError
    if options[:raise]
      raise InvalidNumberError, number
    else
      return number
    end
  end
  defaults = I18n.translate(:'number.format', :locale => options[:locale], :default => {})
  human    = I18n.translate(:'number.human.format', :locale => options[:locale], :default => {})
  defaults = defaults.merge(human)
  options = options.reverse_merge(defaults)
  #for backwards compatibility with those that didn't add strip_insignificant_zeros to their locale files
  options[:strip_insignificant_zeros] = true if not options.key?(:strip_insignificant_zeros)
  units = options.delete :units
  unit_exponents = case units
  when Hash
    units
  when String, Symbol
    I18n.translate(:"#{units}", :locale => options[:locale], :raise => true)
  when nil
    I18n.translate(:"number.human.decimal_units.units", :locale => options[:locale], :raise => true)
  else
    raise ArgumentError, ":units must be a Hash or String translation scope."
  end.keys.map{|e_name| DECIMAL_UNITS.invert[e_name] }.sort_by{|e| -e}
  number_exponent = Math.log10(number).floor
  display_exponent = unit_exponents.find{|e| number_exponent >= e }
  number  /= 10 ** display_exponent
  unit = case units
  when Hash
    units[DECIMAL_UNITS[display_exponent]]
  when String, Symbol
    I18n.translate(:"#{units}.#{DECIMAL_UNITS[display_exponent]}", :locale => options[:locale], :count => number.to_i)
  else
    I18n.translate(:"number.human.decimal_units.units.#{DECIMAL_UNITS[display_exponent]}", :locale => options[:locale], :count => number.to_i)
  end
  decimal_format = options[:format] || I18n.translate(:'number.human.decimal_units.format', :locale => options[:locale], :default => "%n %u")
  formatted_number = number_with_precision(number, options)
  decimal_format.gsub(/%n/, formatted_number).gsub(/%u/, unit).strip.html_safe
end