Kode #61: hints & solution
Here's the clue board for Kode #61. 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.
- 16725▲1●1
- 26753▲0●2
- 38379▲0●2
- 45196▲0●2
- 52649▲0●0
Spoiler-free hints
- Exactly one of the four digits is even.
- The four digits add up to 21.
- 3 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 5 (2 6 4 9) has no marks at all, so 2, 6, 4, and 9 are not in the code.
- Row 1 (6 7 2 5) has 2 marks still unexplained, and only 2 digits are left undecided: 7 and 5. So both are in the code.
- Row 2 (6 7 5 3) has 2 marks, already accounted for by 7 and 5. That rules out 3.
- Row 3 (8 3 7 9) has one mark still unexplained, and only one digit is left undecided: 8. So it is in the code.
- Row 4 (5 1 9 6) has one mark still unexplained, and only one digit is left undecided: 1. So it is in the code.
- That makes all four digits of the code: 1, 5, 7, and 8. Every other digit is out, which also rules out 0.
- Row 1 (6 7 2 5) has one digit in the right spot. Since row 2 rules out the 7 in position 2, it has to be the 5 in position 4.
- The 7 has only one spot left: position 1 (row 2 rules out position 2, row 3 rules out position 3, and position 4 is already 5).
- The 1 has only one spot left: position 3 (row 4 rules out position 2, position 1 is already 7, and position 4 is already 5).
- That leaves the 8 for position 2.
That cracks it: the code is 7815.