Find integers n whose reciprocal has n-1 repeating digits

long_repeaters.rb

MAX_DIGITS = 1000

7.upto(MAX_DIGITS) do |i|
  scaled_reciprocal = (10**(i*2)) / i
  digits = sprintf("%0#{2*i}d", scaled_reciprocal)
  # printf "%d -> 0.%s...\n", i, digits
  first_repeat = nil
  offset = nil
  1.upto(i-1) do |r|
    # Break the digits into as many groups of r characters as possible
    repetitions = digits.scan(/.{#{r}}/)
    if repetitions.uniq.size == 1     # All the groups are identical
      # puts "\trepeats #{repetitions[0]}"
      first_repeat = r unless first_repeat
    end
  end

  if first_repeat == i-1
    puts "\t1/#{i} = 0.`#{digits[0,first_repeat]}`"
  end
end