Kode #21: hints & solution
Here's the clue board for Kode #21. 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.
- 14685▲1●1
- 24035▲0●1
- 33601▲1●1
- 48290▲0●0
- 52874▲0●2
Spoiler-free hints
- 2 of the four digits are even.
- The four digits add up to 18.
- 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 (8 2 9 0) has no marks at all, so 8, 2, 9, and 0 are not in the code.
- Row 5 (2 8 7 4) has 2 marks still unexplained, and only 2 digits are left undecided: 7 and 4. So both are in the code.
- Row 2 (4 0 3 5) has one mark, already accounted for by 4. That rules out 3 and 5.
- Row 1 (4 6 8 5) has one mark still unexplained, and only one digit is left undecided: 6. So it is in the code.
- Row 3 (3 6 0 1) has one mark still unexplained, and only one digit is left undecided: 1. So it is in the code.
- Row 1 (4 6 8 5) has one digit in the right spot. Since row 2 rules out the 4 in position 1, it has to be the 6 in position 2.
- Row 3 (3 6 0 1) has only one digit in the right spot, already accounted for by the 6 in position 2. So the 1 isn't in position 4.
- The 4 has only one spot left: position 3 (row 2 rules out position 1, row 5 rules out position 4, and position 2 is already 6).
- The 1 has only one spot left: position 1 (row 3 rules out position 4, position 2 is already 6, and position 3 is already 4).
- That leaves the 7 for position 4.
That cracks it: the code is 1647.