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Kode #110: hints & solution

Here's the clue board for Kode #110. 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.

  • 12547▲1●1
  • 22580▲0●1
  • 30625▲0●2
  • 47918▲0●2
  • 53549▲0●0

Spoiler-free hints

  • 2 of the four digits are even.
  • The four digits add up to 16.
  • 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 (3 5 4 9) has no marks at all, so 3, 5, 4, and 9 are not in the code.
  2. Row 1 (2 5 4 7) has 2 marks still unexplained, and only 2 digits are left undecided: 2 and 7. So both are in the code.
  3. Row 2 (2 5 8 0) has one mark, already accounted for by 2. That rules out 8 and 0.
  4. Row 3 (0 6 2 5) has one mark still unexplained, and only one digit is left undecided: 6. So it is in the code.
  5. Row 4 (7 9 1 8) has one mark still unexplained, and only one digit is left undecided: 1. So it is in the code.
  6. Row 1 (2 5 4 7) has one digit in the right spot. Since row 2 rules out the 2 in position 1, it has to be the 7 in position 4.
  7. The 2 has only one spot left: position 2 (row 2 rules out position 1, row 3 rules out position 3, and position 4 is already 7).
  8. The 1 has only one spot left: position 1 (row 4 rules out position 3, position 2 is already 2, and position 4 is already 7).
  9. That leaves the 6 for position 3.

That cracks it: the code is 1267.

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