#!/usr/bin/env ruby

def digits(num)
  result = []
  numbers = num.to_s.split('').map { |n| n.to_i }
  numbers.each_with_index do |number, index|
    following = numbers[(index + 1)..]
    following.each do |other|
      result << number + other
    end
  end
  result
end

num = 123
puts digits(num)

# Additionner avec > que lui puis donner la somme
# 1 + 2 = 3
# 1 + 3 = 4
# 2 + 3 = 5