Kode #24: hints & solution

Here's the clue board for Kode #24. Start with the spoiler-free hints. If you're still stuck, the full step-by-step solution is below, hidden until you open it.

The clue board

Each row is a guess that's already been graded. ▲ means a right digit in the right spot; ● means a right digit in the wrong spot.

  • 12765▲1●1
  • 22067▲0●2
  • 30826▲1●1
  • 41927▲0●2
  • 52903▲0●0

Spoiler-free hints

  • 2 of the four digits are even.
  • The four digits add up to 22.
  • 3 of the digits are 5 or higher.

Try the hints first. The solution below walks through every deduction.

Step-by-step solution

Every Kode can be cracked by pure deduction, with no guessing. This board falls in 10 logical steps. Open the solution to follow them one at a time.

Show the solution · reveals the code

When a row "rules out" a position, it shows that digit there but its ▲ marks are already used up (or it has none), so the digit can't sit there.

  1. Row 5 (2 9 0 3) has no marks at all, so 2, 9, 0, and 3 are not in the code.
  2. Row 2 (2 0 6 7) has 2 marks still unexplained, and only 2 digits are left undecided: 6 and 7. So both are in the code.
  3. Row 1 (2 7 6 5) has 2 marks, already accounted for by 7 and 6. That rules out 5.
  4. Row 3 (0 8 2 6) has one mark still unexplained, and only one digit is left undecided: 8. So it is in the code.
  5. Row 4 (1 9 2 7) has one mark still unexplained, and only one digit is left undecided: 1. So it is in the code.
  6. That makes all four digits of the code: 1, 6, 7, and 8. Every other digit is out, which also rules out 4.
  7. Row 1 (2 7 6 5) has one digit in the right spot. Since row 2 rules out the 6 in position 3, it has to be the 7 in position 2.
  8. Row 3 (0 8 2 6) has one digit in the right spot. Since position 2 is already 7, it has to be the 6 in position 4.
  9. The 1 has only one spot left: position 3 (row 4 rules out position 1, position 2 is already 7, and position 4 is already 6).
  10. That leaves the 8 for position 1.

That cracks it: the code is 8716.