Kode #65: hints & solution
Here's the clue board for Kode #65. 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.
- 17641▲1●1
- 27609▲0●1
- 36372▲0●1
- 47981▲0●2
- 57286▲0●0
Spoiler-free hints
- Exactly one of the four digits is even.
- The four digits add up to 17.
- 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 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 5 (7 2 8 6) has no marks at all, so 7, 2, 8, and 6 are not in the code.
- Row 1 (7 6 4 1) has 2 marks still unexplained, and only 2 digits are left undecided: 4 and 1. So both are in the code.
- Row 3 (6 3 7 2) has one mark still unexplained, and only one digit is left undecided: 3. So it is in the code.
- Row 4 (7 9 8 1) has one mark still unexplained, and only one digit is left undecided: 9. So it is in the code.
- Row 2 (7 6 0 9) has one mark, already accounted for by 9. That rules out 0.
- That makes all four digits of the code: 1, 3, 4, and 9. Every other digit is out, which also rules out 5.
- Row 1 (7 6 4 1) has one digit in the right spot. Since row 4 rules out the 1 in position 4, it has to be the 4 in position 3.
- The 9 has only one spot left: position 1 (row 4 rules out position 2, row 2 rules out position 4, and position 3 is already 4).
- The 1 has only one spot left: position 2 (row 4 rules out position 4, position 1 is already 9, and position 3 is already 4).
- That leaves the 3 for position 4.
That cracks it: the code is 9143.