Number lock puzzle 9285: Can you crack the 4 digit number lock code from the five clues? Each 4 digit clue hints on correct digits and placements.
The 4 digit number lock puzzle 9285
Find the 4 digit code from the five clues to unlock the number lock:
- Clue 1: Code 9 2 8 5 : One digit right but in wrong position.
- Clue 2: Code 1 9 3 7 : Two digits are correct but wrongly placed.
- Clue 3: Code 5 2 0 1 : One digit is correct and well placed.
- Clue 4: Code 6 5 0 7 : Nothing is correct.
- Clue 5: Code 8 5 2 4 : Two digits right but wrongly placed.
Solution to the 4 digit number lock puzzle 9285
First objective to solve a 4 digit number lock riddle with 5 clues must be,
- To eliminate as many as digits as possible from the set of possible 10 digits.
Second objective must be to,
- Identify the correct digits from the short-listed possible digits.
And the third objective is to,
- Identify the placement of the correct digits.
Step 1: Clue 4 eliminates maximum number of possible digits
Clue 4: Code 6 5 0 7 : Nothing is correct.
Digits 6, 5, 0 and 7 are eliminated at one go.
- Possible correct digits 1, 2, 3, 4, 8 and 9.
Step 2: Identify correct or incorrect digits: Breakthrough in the number lock riddle
No other clue alone identifies a correct or incorrect digit.
- More than one clue must be used together.
This is where conflict of correctness and position help. Such a conflict for digit 2 arises in Clue 1 and Clue 3.
Clue 1: Code 9 2 8 5 : One digit right but in wrong position.
Clue 3: Code 5 2 0 1 : One digit is correct and well placed.
Digit 2 appears in both clues in 2nd position, but in Clue 1, correct digit is wrongly placed and in Clue 3, it is well placed.
- Digit 2 must be a wrong digit. It cannot be a correct digit.
- Possible correct digits are 1, 3, 4, 8 or 9.
This is the most important breakthrough in the puzzle.
Step 3: Identify more correct and incorrect digits
Clue 5 stands out. With digit 2 identified as incorrect, only two possible correct digits 4 and 8 are used in the clue.
Clue 5: Code 8 5 2 4 : Two digits right but wrongly placed.
- Digits 4 and 8 are confirmed correct.
- Other possible correct digits are 1, 3 and 9.
Now Clue 3 gives us one more correct digit as well as its position.
Clue 3: Code 5 2 0 1 : One digit is correct and well placed.
With digit 2 identified as incorrect, only digit 1 is a possible correct digit left.
- Digit 1 must be the correct digit and its position is also certain as the 4th.
- Possible correct digits are digits 3 and 9.
With digit 2 identified as incorrect and digit 8 correct, Clue 1 gives us the final breakthrough on correctness of digits (but not on positions).
Clue 1: Code 9 2 8 5 : One digit right but in wrong position.
- Digit 9 must be the incorrect digit when digit 8 is correct.
- The only possible candidate left 3 is the fourth correct digit.
- The correct digits are 4, 8, 1 and 3.
Step 4: Placement analysis of digit 8 from Clue 1 and Clue 5
Clue 1: Code 9 2 8 5 : One digit right but in wrong position.
Clue 5: Code 8 5 2 4 : Two digits right but wrongly placed.
Digit 8 appears in Clue 1 in 3rd position and in Clue 5 in 1st position, and both are wrong.
- Position of digit 8 must be the 2nd (4th is already occupied by digit 1).
- Digits 3 and 4 are to be correctly placed in the 1st and 3rd position left.
Step 5: Final solution of the number lock riddle by placement analysis
Digit 3 appears only in Clue 2. This will give us the solution.
Clue 2: Code 1 9 3 7 : Two digits are correct but wrongly placed.
- 3rd position for digit 3 is wrong. The only position left for it is the 1st (as 2nd and 4th already fixed).
- Position of digit 4 is the 3rd, the only position still not fixed.
The number lock code to open the lock is 3 8 4 1.
Verify the correctness of the code by tallying the code with each of the five clues.
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