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Kode #120: hints & solution

Here's the clue board for Kode #120. 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.

  • 19284▲1●1
  • 29216▲0●1
  • 35739▲0●2
  • 45217▲0●0
  • 52045▲1●1

Spoiler-free hints

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

That cracks it: the code is 3094.

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