Kode #85: hints & solution
Here's the clue board for Kode #85. 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.
- 19687▲1●1
- 20385▲0●2
- 32531▲0●2
- 43690▲0●0
- 50892▲0●1
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 4 (3 6 9 0) has no marks at all, so 3, 6, 9, and 0 are not in the code.
- Row 1 (9 6 8 7) has 2 marks still unexplained, and only 2 digits are left undecided: 8 and 7. So both are in the code.
- Row 2 (0 3 8 5) has one mark still unexplained, and only one digit is left undecided: 5. So it is in the code.
- Row 5 (0 8 9 2) has one mark, already accounted for by 8. That rules out 2.
- Row 3 (2 5 3 1) 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 4.
- Row 1 (9 6 8 7) has one digit in the right spot. Since row 2 rules out the 8 in position 3, it has to be the 7 in position 4.
- The 8 has only one spot left: position 1 (row 5 rules out position 2, row 2 rules out position 3, and position 4 is already 7).
- The 5 has only one spot left: position 3 (row 3 rules out position 2, position 1 is already 8, and position 4 is already 7).
- That leaves the 1 for position 2.
That cracks it: the code is 8157.