Kode #1: hints & solution
Here's the clue board for Kode #1. 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.
- 18506▲1●1
- 28076▲0●1
- 33147▲0●2
- 48462▲0●0
- 50365▲0●3
Spoiler-free hints
- Exactly one of the four digits is even.
- The four digits add up to 9.
- 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 4 (8 4 6 2) has no marks at all, so 8, 4, 6, and 2 are not in the code.
- Row 1 (8 5 0 6) has 2 marks still unexplained, and only 2 digits are left undecided: 5 and 0. So both are in the code.
- Row 2 (8 0 7 6) has one mark, already accounted for by 0. That rules out 7.
- Row 3 (3 1 4 7) has 2 marks still unexplained, and only 2 digits are left undecided: 3 and 1. So both are in the code.
- That makes all four digits of the code: 0, 1, 3, and 5. Every other digit is out, which also rules out 9.
- Position 2 can only be 5 (row 2 rules out 0, row 3 rules out 1, and row 5 rules out 3).
- Row 1 (8 5 0 6) has only one digit in the right spot, already accounted for by the 5 in position 2. So the 0 isn't in position 3.
- The 0 has only one spot left: position 4 (row 5 rules out position 1, row 1 rules out position 3, and position 2 is already 5).
- The 3 has only one spot left: position 3 (row 3 rules out position 1, position 2 is already 5, and position 4 is already 0).
- That leaves the 1 for position 1.
That cracks it: the code is 1530.