Kode #121: hints & solution
Here's the clue board for Kode #121. 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.
- 10785▲1●1
- 20235▲0●1
- 33420▲1●0
- 40918▲1●1
- 50413▲0●0
Spoiler-free hints
- 2 of the four digits are even.
- The four digits add up to 26.
- 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 (0 4 1 3) has no marks at all, so 0, 4, 1, and 3 are not in the code.
- Row 3 (3 4 2 0) has one mark still unexplained, and only one digit is left undecided: 2. So it is in the code.
- Row 2 (0 2 3 5) has one mark, already accounted for by 2. That rules out 5.
- Row 1 (0 7 8 5) has 2 marks still unexplained, and only 2 digits are left undecided: 7 and 8. So both are in the code.
- Row 4 (0 9 1 8) has one mark still unexplained, and only one digit is left undecided: 9. So it is in the code.
- That makes all four digits of the code: 2, 7, 8, and 9. Every other digit is out, which also rules out 6.
- Row 3 (3 4 2 0) has one digit in the right spot, and the 2 in position 3 is its only digit in the code, so it's locked in.
- Row 1 (0 7 8 5) has one digit in the right spot. Since position 3 is already 2, it has to be the 7 in position 2.
- Row 4 (0 9 1 8) has one digit in the right spot. Since position 2 is already 7, it has to be the 8 in position 4.
- That leaves the 9 for position 1.
That cracks it: the code is 9728.