Kode #20: hints & solution
Here's the clue board for Kode #20. 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.
- 17426▲1●1
- 27108▲0●2
- 33974▲0●2
- 44638▲0●0
- 59182▲0●3
Spoiler-free hints
- Exactly one of the four digits is even.
- The four digits add up to 19.
- 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 (4 6 3 8) has no marks at all, so 4, 6, 3, and 8 are not in the code.
- Row 1 (7 4 2 6) has 2 marks still unexplained, and only 2 digits are left undecided: 7 and 2. So both are in the code.
- Row 3 (3 9 7 4) has one mark still unexplained, and only one digit is left undecided: 9. So it is in the code.
- Row 5 (9 1 8 2) has one mark still unexplained, and only one digit is left undecided: 1. So it is in the code.
- Row 2 (7 1 0 8) has 2 marks, already accounted for by 7 and 1. That rules out 0.
- That makes all four digits of the code: 1, 2, 7, and 9. Every other digit is out, which also rules out 5.
- Row 1 (7 4 2 6) has one digit in the right spot. Since row 2 rules out the 7 in position 1, it has to be the 2 in position 3.
- The 9 has only one spot left: position 4 (row 5 rules out position 1, row 3 rules out position 2, and position 3 is already 2).
- The 1 has only one spot left: position 1 (row 2 rules out position 2, position 3 is already 2, and position 4 is already 9).
- That leaves the 7 for position 2.
That cracks it: the code is 1729.