Kode #19: hints & solution
Here's the clue board for Kode #19. 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.
- 16735▲1●1
- 28719▲0●2
- 31842▲0●2
- 44398▲1●1
- 56951▲0●0
Spoiler-free hints
- 2 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 5 (6 9 5 1) has no marks at all, so 6, 9, 5, and 1 are not in the code.
- Row 1 (6 7 3 5) has 2 marks still unexplained, and only 2 digits are left undecided: 7 and 3. So both are in the code.
- Row 2 (8 7 1 9) has one mark still unexplained, and only one digit is left undecided: 8. So it is in the code.
- Row 4 (4 3 9 8) has 2 marks, already accounted for by 3 and 8. That rules out 4.
- Row 3 (1 8 4 2) has one mark still unexplained, and only one digit is left undecided: 2. So it is in the code.
- That makes all four digits of the code: 2, 3, 7, and 8. Every other digit is out, which also rules out 0.
- Row 1 (6 7 3 5) has one digit in the right spot. Since row 2 rules out the 7 in position 2, it has to be the 3 in position 3.
- Row 4 (4 3 9 8) has one digit in the right spot. Since the 3 is already in position 3, it has to be the 8 in position 4.
- The 7 has only one spot left: position 1 (row 2 rules out position 2, position 3 is already 3, and position 4 is already 8).
- That leaves the 2 for position 2.
That cracks it: the code is 7238.