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Kode #102: hints & solution

Here's the clue board for Kode #102. 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.

  • 14501▲1●1
  • 25301▲0●1
  • 37238▲0●2
  • 47480▲1●2
  • 58619▲0●0

Spoiler-free hints

  • 3 of the four digits are even.
  • The four digits add up to 13.
  • 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 (8 6 1 9) has no marks at all, so 8, 6, 1, and 9 are not in the code.
  2. Row 4 (7 4 8 0) has 3 marks still unexplained, and only 3 digits are left undecided: 7, 4, and 0. So all of them are in the code.
  3. Row 1 (4 5 0 1) has 2 marks, already accounted for by 4 and 0. That rules out 5.
  4. Row 2 (5 3 0 1) has one mark, already accounted for by 0. That rules out 3.
  5. Row 3 (7 2 3 8) has one mark still unexplained, and only one digit is left undecided: 2. So it is in the code.
  6. Row 1 (4 5 0 1) has one digit in the right spot. Since row 2 rules out the 0 in position 3, it has to be the 4 in position 1.
  7. Row 4 (7 4 8 0) has one digit in the right spot. Since position 1 is already 4 and the 4 is already in position 1, it has to be the 0 in position 4.
  8. The 2 has only one spot left: position 3 (row 3 rules out position 2, position 1 is already 4, and position 4 is already 0).
  9. That leaves the 7 for position 2.

That cracks it: the code is 4720.

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