### Number lock puzzle with 5 clues including 682

In this number lock puzzle with 5 clues including 682 in code, each clue describes position and correctness of 3 digits in its code. Can you crack the code? **Try for the most efficient solution.**

Following shows five clues each with a three-digit code for a number lock and descriptions of the digit positions. Find the code to open the lock from the clues.

**Clue 1: Code 682:** One digit is right and is in its place.

**Clue 2: Code 645:** One digit is right and is in the wrong place.

**Clue 3: Code 206:** Two digits are right, but both are in the wrong place.

**Clue 4: Code 738:** All digits are wrong.

**Clue 5: Code 780:** One digit right and is in the wrong place.

From these five clues, find the three-digit code that will open the number lock.

### Solution to number lock puzzle with 5 clues including 682

#### Identify correct or incorrect digits

No clue alone can identify a correct or incorrect digit.

- More than one suitable clue with same digit appearing, but with conflcting position description will serve our purpose.

Such clues are Clue 1 and Clue 6.

**Clue 1: Code 682:** One digit is right and is in its place.

**Clue 2: Code 645:** One digit is right and is in the wrong place.

- Digit 6 cannot occupy the same position in both and have correct place in one clue and wrong place in the other.
**Digit 6 is the first wrong digit identified.**

Take up next Clue 3 as it includes wrong digit 6.

**Clue 3: Code 206:** Two digits are right, but both are in the wrong place.

- With digit 6 wrong, first
**two correct digits identified are 0 and 2.**

#### Find the correct digit placements

Take up Clue 1 again as its code includes correct digit 2.

**Clue 1: Code 682:** One digit is right and is in its place.

- Digit 2 is to be placed in the rightmost position.

**Turn to Clue 3 again** in which two correct digits 0 and 2 both are wrongly placed.

Rightmost position already taken up and middle position for digit 0 is wrong.

- Position of digit 0 must be leftmost.
- Correct code is of the form 0 ? 2.

#### Find the third right digit for solution of the 3 digit number lock riddle with 5 clues

Analyze Clue 2 with two possible correct digits 4 and 5.

**Clue 2: Code 645:** One digit is right and is in the wrong place.

The correct digit is in the wrong place.

- Digit 4 occupying the only available supposedly correct position cannot be the right digit.
**The third right digit is 5 in middle position.**

The **code to open the lock is 0 5 2.**

*The clues 4 and 5 not needed.* **This is the most efficient solution.**

#### End note

The key to quick solution of reasoning puzzles is processing the most suitable clue or condition either individually or together with other clues.

To enjoy solving many more such number lock puzzles, click **here.**

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