← All puzzles

Kode #99: hints & solution

Here's the clue board for Kode #99. 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.

  • 17129▲1●1
  • 28039▲0●2
  • 30968▲1●1
  • 42543▲1●0
  • 54397▲0●0

Spoiler-free hints

  • 3 of the four digits are even.
  • The four digits add up to 11.
  • 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 (4 3 9 7) has no marks at all, so 4, 3, 9, and 7 are not in the code.
  2. Row 1 (7 1 2 9) has 2 marks still unexplained, and only 2 digits are left undecided: 1 and 2. So both are in the code.
  3. Row 2 (8 0 3 9) has 2 marks still unexplained, and only 2 digits are left undecided: 8 and 0. So both are in the code.
  4. Row 3 (0 9 6 8) has 2 marks, already accounted for by 0 and 8. That rules out 6.
  5. Row 4 (2 5 4 3) has one mark, already accounted for by 2. That rules out 5.
  6. Row 4 (2 5 4 3) has one digit in the right spot, and the 2 in position 1 is its only digit in the code, so it's locked in.
  7. Row 1 (7 1 2 9) has one digit in the right spot. Since the 2 is already in position 1, it has to be the 1 in position 2.
  8. Row 3 (0 9 6 8) has one digit in the right spot. Since position 1 is already 2, it has to be the 8 in position 4.
  9. That leaves the 0 for position 3.

That cracks it: the code is 2108.

Play today's Kode