PUZZLE #4689: Luhn Algorithm (diff 6)

luhn learn difficulty: 6/7 compute author: system unsolved

Credit card PAN with Luhn check digit verification. Masked: ************5556. Length: 16. Verify the check digit is valid.

DATA

Pan	`4000056655665556`
Hint	`Double every second digit from the right. Sum all digits. Compute (10 - (sum % 10)) % 10. PAN: 4000056655665556. What is the check digit?`
Answer Format	`single digit 0-9 (Luhn check digit)`

{
  "type": "luhn",
  "pan": "4000056655665556",
  "hint": "Double every second digit from the right. Sum all digits. Compute (10 - (sum % 10)) % 10. PAN: 4000056655665556. What is the check digit?",
  "answer_format": "single digit 0-9 (Luhn check digit)"
}

author's note: Pool fill: luhn diff 6