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Kode #134: hints & solution

Here's the clue board for Kode #134. 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.

  • 16412▲1●1
  • 26425▲0●2
  • 39614▲1●1
  • 43269▲0●2
  • 59804▲0●0

Spoiler-free hints

  • Exactly one of the four digits is even.
  • The four digits add up to 15.
  • 2 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 11 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 (9 8 0 4) has no marks at all, so 9, 8, 0, and 4 are not in the code.
  2. Row 3 (9 6 1 4) has 2 marks still unexplained, and only 2 digits are left undecided: 6 and 1. So both are in the code.
  3. Row 1 (6 4 1 2) has 2 marks, already accounted for by 6 and 1. That rules out 2.
  4. Row 2 (6 4 2 5) has one mark still unexplained, and only one digit is left undecided: 5. So it is in the code.
  5. Row 4 (3 2 6 9) has one mark still unexplained, and only one digit is left undecided: 3. So it is in the code.
  6. That makes all four digits of the code: 1, 3, 5, and 6. Every other digit is out, which also rules out 7.
  7. Row 1 (6 4 1 2) has one digit in the right spot. Since row 2 rules out the 6 in position 1, it has to be the 1 in position 3.
  8. Row 3 (9 6 1 4) has only one digit in the right spot, already accounted for by the 1 in position 3. So the 6 isn't in position 2.
  9. The 6 has only one spot left: position 4 (row 2 rules out position 1, row 3 rules out position 2, and position 3 is already 1).
  10. The 3 has only one spot left: position 2 (row 4 rules out position 1, position 3 is already 1, and position 4 is already 6).
  11. That leaves the 5 for position 1.

That cracks it: the code is 5316.

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