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Kode #30: hints & solution

Here's the clue board for Kode #30. 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.

  • 13512▲1●1
  • 23410▲0●1
  • 36703▲0●2
  • 44830▲0●0
  • 59154▲1●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 4 (4 8 3 0) has no marks at all, so 4, 8, 3, and 0 are not in the code.
  2. Row 2 (3 4 1 0) has one mark still unexplained, and only one digit is left undecided: 1. So it is in the code.
  3. Row 3 (6 7 0 3) has 2 marks still unexplained, and only 2 digits are left undecided: 6 and 7. So both are in the code.
  4. Row 5 (9 1 5 4) has one mark, already accounted for by 1. That rules out 9 and 5.
  5. Row 1 (3 5 1 2) has one mark still unexplained, and only one digit is left undecided: 2. So it is in the code.
  6. Row 1 (3 5 1 2) has one digit in the right spot. Since row 2 rules out the 1 in position 3, it has to be the 2 in position 4.
  7. Row 5 (9 1 5 4) has one digit in the right spot, and the 1 in position 2 is its only digit in the code, so it's locked in.
  8. The 6 has only one spot left: position 3 (row 3 rules out position 1, position 2 is already 1, and position 4 is already 2).
  9. That leaves the 7 for position 1.

That cracks it: the code is 7162.

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