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Kode #40: hints & solution

Here's the clue board for Kode #40. 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.

  • 11976▲1●1
  • 27946▲0●2
  • 39405▲0●2
  • 49084▲0●2
  • 59685▲0●0

Spoiler-free hints

  • 2 of the four digits are even.
  • The four digits add up to 12.
  • Just one digit is 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 (9 6 8 5) has no marks at all, so 9, 6, 8, and 5 are not in the code.
  2. Row 1 (1 9 7 6) has 2 marks still unexplained, and only 2 digits are left undecided: 1 and 7. So both are in the code.
  3. Row 2 (7 9 4 6) has one mark still unexplained, and only one digit is left undecided: 4. So it is in the code.
  4. Row 3 (9 4 0 5) has one mark still unexplained, and only one digit is left undecided: 0. So it is in the code.
  5. That makes all four digits of the code: 0, 1, 4, and 7. Every other digit is out, which also rules out 2 and 3.
  6. The 4 has only one spot left: position 1 (row 3 rules out position 2, row 2 rules out position 3, and row 4 rules out position 4).
  7. Row 1 (1 9 7 6) has one digit in the right spot. Since position 1 is already 4, it has to be the 7 in position 3.
  8. The 0 has only one spot left: position 4 (row 4 rules out position 2, position 1 is already 4, and position 3 is already 7).
  9. That leaves the 1 for position 2.

That cracks it: the code is 4170.

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