Kode #78: hints & solution
Here's the clue board for Kode #78. 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.
- 11376▲1●1
- 21975▲0●1
- 39702▲0●2
- 48954▲0●0
- 58216▲1●2
Spoiler-free hints
- 3 of the four digits are 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 9 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 9 5 4) has no marks at all, so 8, 9, 5, and 4 are not in the code.
- Row 5 (8 2 1 6) has 3 marks still unexplained, and only 3 digits are left undecided: 2, 1, and 6. So all of them are in the code.
- Row 1 (1 3 7 6) has 2 marks, already accounted for by 1 and 6. That rules out 3 and 7.
- Row 3 (9 7 0 2) has one mark still unexplained, and only one digit is left undecided: 0. So it is in the code.
- Row 1 (1 3 7 6) has one digit in the right spot. Since row 2 rules out the 1 in position 1, it has to be the 6 in position 4.
- Row 5 (8 2 1 6) has only one digit in the right spot, already accounted for by the 6 in position 4. So the 2 isn't in position 2 and the 1 isn't in position 3.
- The 1 has only one spot left: position 2 (row 2 rules out position 1, row 5 rules out position 3, and position 4 is already 6).
- The 0 has only one spot left: position 1 (row 3 rules out position 3, position 2 is already 1, and position 4 is already 6).
- That leaves the 2 for position 3.
That cracks it: the code is 0126.