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Kode #118: hints & solution

Here's the clue board for Kode #118. 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.

  • 16941▲1●1
  • 20721▲0●2
  • 36547▲1●1
  • 40897▲0●0
  • 58147▲0●1

Spoiler-free hints

  • 2 of the four digits are even.
  • The four digits add up to 14.
  • 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 4 (0 8 9 7) has no marks at all, so 0, 8, 9, and 7 are not in the code.
  2. Row 2 (0 7 2 1) has 2 marks still unexplained, and only 2 digits are left undecided: 2 and 1. So both are in the code.
  3. Row 5 (8 1 4 7) has one mark, already accounted for by 1. That rules out 4.
  4. Row 1 (6 9 4 1) has one mark still unexplained, and only one digit is left undecided: 6. So it is in the code.
  5. Row 3 (6 5 4 7) has one mark still unexplained, and only one digit is left undecided: 5. So it is in the code.
  6. That makes all four digits of the code: 1, 2, 5, and 6. Every other digit is out, which also rules out 3.
  7. Row 1 (6 9 4 1) has one digit in the right spot. Since row 2 rules out the 1 in position 4, it has to be the 6 in position 1.
  8. Row 3 (6 5 4 7) has only one digit in the right spot, already accounted for by the 6 in position 1. So the 5 isn't in position 2.
  9. The 1 has only one spot left: position 3 (row 5 rules out position 2, row 2 rules out position 4, and position 1 is already 6).
  10. The 5 has only one spot left: position 4 (row 3 rules out position 2, position 1 is already 6, and position 3 is already 1).
  11. That leaves the 2 for position 2.

That cracks it: the code is 6215.

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