fun-function.rb

#!/usr/bin/ruby

last = 1

def num1(num)
  result = 0
  while num > 0
    if num % 10 == 1
      result += 1
    end
    num = num / 10
  end
  result
end

2.upto(10000000) do |i|
  fn = last + num1(i)
  if fn == i
    puts fn
    break
  end
  last = fn

  puts i if i % 1000 == 0
end