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Kode #179: hints & solution

Here's the clue board for Kode #179. 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.

  • 10687▲1●1
  • 21382▲0●2
  • 30637▲1●1
  • 45379▲0●0
  • 54762▲1●1

Spoiler-free hints

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

That cracks it: the code is 0261.

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