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Kode #171: hints & solution

Here's the clue board for Kode #171. 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.

  • 11382▲1●1
  • 26982▲0●1
  • 37806▲0●2
  • 46574▲1●1
  • 58024▲0●0

Spoiler-free hints

  • Exactly one of the four digits is even.
  • The four digits add up to 17.
  • 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 9 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 (8 0 2 4) has no marks at all, so 8, 0, 2, and 4 are not in the code.
  2. Row 1 (1 3 8 2) has 2 marks still unexplained, and only 2 digits are left undecided: 1 and 3. So both are in the code.
  3. Row 3 (7 8 0 6) has 2 marks still unexplained, and only 2 digits are left undecided: 7 and 6. So both are in the code.
  4. Row 2 (6 9 8 2) has one mark, already accounted for by 6. That rules out 9.
  5. Row 4 (6 5 7 4) has 2 marks, already accounted for by 6 and 7. That rules out 5.
  6. Row 4 (6 5 7 4) has one digit in the right spot. Since row 2 rules out the 6 in position 1, it has to be the 7 in position 3.
  7. The 6 has only one spot left: position 2 (row 2 rules out position 1, row 3 rules out position 4, and position 3 is already 7).
  8. Row 1 (1 3 8 2) has one digit in the right spot. Since position 2 is already 6, it has to be the 1 in position 1.
  9. That leaves the 3 for position 4.

That cracks it: the code is 1673.

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