Kode #91: hints & solution
Here's the clue board for Kode #91. 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.
- 13924▲1●1
- 23829▲0●2
- 38136▲0●2
- 45310▲0●0
- 52318▲0●2
Spoiler-free hints
- 4 of the four digits are even.
- The four digits add up to 20.
- 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 10 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.
- Row 4 (5 3 1 0) has no marks at all, so 5, 3, 1, and 0 are not in the code.
- Row 3 (8 1 3 6) has 2 marks still unexplained, and only 2 digits are left undecided: 8 and 6. So both are in the code.
- Row 5 (2 3 1 8) has one mark still unexplained, and only one digit is left undecided: 2. So it is in the code.
- Row 2 (3 8 2 9) has 2 marks, already accounted for by 8 and 2. That rules out 9.
- Row 1 (3 9 2 4) has one mark still unexplained, and only one digit is left undecided: 4. So it is in the code.
- That makes all four digits of the code: 2, 4, 6, and 8. Every other digit is out, which also rules out 7.
- Row 1 (3 9 2 4) has one digit in the right spot. Since row 2 rules out the 2 in position 3, it has to be the 4 in position 4.
- The 2 has only one spot left: position 2 (row 5 rules out position 1, row 2 rules out position 3, and position 4 is already 4).
- The 8 has only one spot left: position 3 (row 3 rules out position 1, position 2 is already 2, and position 4 is already 4).
- That leaves the 6 for position 1.
That cracks it: the code is 6284.