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Kode #112: hints & solution

Here's the clue board for Kode #112. 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.

  • 14319▲1●1
  • 20679▲0●2
  • 35942▲0●2
  • 43842▲0●0
  • 57804▲0●0

Spoiler-free hints

  • Exactly one of the four digits is even.
  • The four digits add up to 21.
  • 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 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 4 (3 8 4 2) has no marks at all, so 3, 8, 4, and 2 are not in the code.
  2. Row 1 (4 3 1 9) has 2 marks still unexplained, and only 2 digits are left undecided: 1 and 9. So both are in the code.
  3. Row 3 (5 9 4 2) has one mark still unexplained, and only one digit is left undecided: 5. So it is in the code.
  4. Row 5 (7 8 0 4) has no marks at all, so 7 and 0 are not in the code.
  5. Row 2 (0 6 7 9) has one mark still unexplained, and only one digit is left undecided: 6. So it is in the code.
  6. Row 1 (4 3 1 9) has one digit in the right spot. Since row 2 rules out the 9 in position 4, it has to be the 1 in position 3.
  7. The 9 has only one spot left: position 1 (row 3 rules out position 2, row 2 rules out position 4, and position 3 is already 1).
  8. The 6 has only one spot left: position 4 (row 2 rules out position 2, position 1 is already 9, and position 3 is already 1).
  9. That leaves the 5 for position 2.

That cracks it: the code is 9516.

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