Can you solve the 4 digit combination lock puzzle from 4 clues? Each clue provides hints on a 4 digit code and the placements of digits.

## The 4 digit number lock puzzle with 4 clues and 2439 in clues

Find the 4 digit code from the four clues to unlock the combination lock:

**Clue 1: Code 2 4 3 9 :** Two digits are correct but wrongly placed.

**Clue 2: Code 6 7 3 4 :** Two digits are correct and well placed.

**Clue 3: Code 7 9 1 6 :** One digit is correct but in wrong position.

**Clue 4: Code 3 8 1 7 :** One digit is correct and well placed.

*This puzzle falls in crack the code, combination lock code or number lock puzzles.*

### Solution to the 4 digit number lock puzzle 2439

#### Identify three incorrect digits

From Clue 1 and 2, digit 3 is wrong by position and correctness conflict.

**Clue 1: Code 2 4 3 9 :** Two digits are correct but wrongly placed.

**Clue 2: Code 6 7 3 4 :** Two digits are correct and well placed.

- Digit 3 cannot be correct in both clues, be well placed in one and wrongly placed in the other, but occupying the same 3rd position in both.
**Digit 3 is incorrect.**

From Clue 3 and 4, digit 1 is wrong by position and correctness conflict.

**Clue 3: Code 7 9 1 6 :** One digit is correct but in wrong position.

**Clue 4: Code 3 8 1 7 :** One digit is correct and well placed.

- Digit 1 cannot be correct in both clues, be well placed in one and wrongly placed in the other, but occupying the same 3rd position in both.
**Digit 1 is incorrect.**

From Clue 2 and 4, digit 7 is an incorrect digit.

**Clue 2: Code 6 7 3 4 :** Two digits are correct and well placed.

**Clue 4: Code 3 8 1 7 :** One digit is correct and well placed.

- Digit 7 cannot be a correct digit, be well placed in both clues but in different position in the clues.
**Digit 7 is the third incorrect digit.**

#### Identify the first correct digit

From Clue 4, digit 8 is the first correct digit identified.

**Clue 4: Code 3 8 1 7 :** One digit is correct and well placed.

- With digits 1, 3 and 7 wrong,
**digit 8 is correct.** **Digit 8 is in its correct position of 2nd in the correct code.**

#### Identify the next two correct digits

From Clue 2, digit 6 and 4 are the next two correct digits.

**Clue 2: Code 6 7 3 4 :** Two digits are correct and well placed.

- With digits 3 and 7 wrong, digits 6 and 4 are the two more correct digits in 1st and 4th positions.
**Code is of the form: 6 8 ? 4.**

#### Identify the last incorrect and correct digits for the solution

From Clue 3, digit 9 is the last incorrect digit.

**Clue 3: Code 7 9 1 6 :** One digit is correct but in wrong position.

- With digit 6 as the only correct digit,
**digit 9 is the last incorrect digit.**

From Clue 1, digit 2 is the fourth correct digit.

**Clue 1: Code 2 4 3 9 :** Two digits are correct but wrongly placed.

- With digits 3 and 9 incorrect and digit 4 correct,
**digit 2 is the fourth correct digit.** **Digit 2 is in 3rd position.**

The 4 digit **combination lock code is 6 8 2 4.**

*Verify the correctness of the code by tallying the code with each of the five clues.*

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