Kode #84: hints & solution
Here's the clue board for Kode #84. 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.
- 12904▲1●1
- 29504▲0●2
- 33145▲0●2
- 45370▲0●2
- 59387▲0●0
Spoiler-free hints
- 2 of the four digits are even.
- The four digits add up to 8.
- Just one digit is 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 (9 3 8 7) has no marks at all, so 9, 3, 8, and 7 are not in the code.
- Row 4 (5 3 7 0) has 2 marks still unexplained, and only 2 digits are left undecided: 5 and 0. So both are in the code.
- Row 2 (9 5 0 4) has 2 marks, already accounted for by 5 and 0. That rules out 4.
- Row 1 (2 9 0 4) has one mark still unexplained, and only one digit is left undecided: 2. So it is in the code.
- Row 3 (3 1 4 5) 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: 0, 1, 2, and 5. Every other digit is out, which also rules out 6.
- Row 1 (2 9 0 4) has one digit in the right spot. Since row 2 rules out the 0 in position 3, it has to be the 2 in position 1.
- The 0 has only one spot left: position 2 (row 2 rules out position 3, row 4 rules out position 4, and position 1 is already 2).
- The 5 has only one spot left: position 3 (row 3 rules out position 4, position 1 is already 2, and position 2 is already 0).
- That leaves the 1 for position 4.
That cracks it: the code is 2051.