How to solve a three-digit code puzzle
Let's find the code, one digit at a time.
This practice puzzle is separate from today's game. We need three different digits. As in the daily puzzle, each clue tells us exactly how many are correct.
| Digits | Clue |
|---|---|
682 | 1 correct digit, right place |
614 | 1 correct digit, wrong place |
208 | 2 correct digits, wrong places |
738 | None correct |
1. Cross out 7, 3 and 8
Start with 738: none correct. That means 7, 3 and 8 cannot appear anywhere in the code. Cross them out in the other clues too.
2. Rule out 6
Look at 682 and 614. Both put 6 first.
If 6 were correct, the first clue would tell us to leave it there. The second would tell us to move it. It cannot do both, so cross out 6.
3. Put 2 last
Back to 682. We have crossed out 6 and 8, so 2 must be its correct digit. The clue says it is in the right place: last.
4. Put 0 first
In 208, two digits are correct but both must move. We have crossed out 8, so those digits are 2 and 0.
The 0 cannot stay in the middle. The last box already holds 2. That leaves the first box for 0.
5. Fill the middle box
In 614, we have ruled out 6. Either 1 or 4 belongs in the code, but it must move.
Only the middle box is empty. The 1 is already in the middle of this clue, so it cannot be the digit that moves. That leaves 4.
Now check all four clues:
682: only 2 is correct, and it is in the right place.614: only 4 is correct, and it moves to the middle.208: 2 and 0 are correct, and both move.738: none of these digits is in the code.
A useful habit
Ask two questions about each digit: does it belong in the code, and does it need to move? A wrong place does not mean a wrong digit.