You are here

3 digit number lock puzzle with 3 clues: Crack the code

3 digit number lock puzzle with 3 clues

The 3 digit number lock puzzle with 3 clues

Given three clues, each with a 3 digit code and hints on correct digits and their placements. Find the correct number lock code from the clues.

Find the 3 digit code from the three clues to unlock the number lock:

Clue 1: Code 4 8 2 : One digit right and in right position.

Clue 2: Code 4 1 6 : One digit right but wrongly placed.

Clue 3: Code 2 0 4 : Two digits right but wrongly placed.

Solution to 3 digit number lock puzzle with 3 clues

First objective to solve a 3 digit number lock riddle with 3 clues:

  • To eliminate as many as digits as possible from the set of possible 10 digits.

Step 1: Eliminate a digit by positional conflict

No clue alone eliminates any of the digits. So,

  • More than one suitable clue together must be used.
  • In the clues, a digit should appear in same position in each but with conflicting placement description.

This is the key to the puzzle.

Such a pair of clues are Clue 1 and Clue 2.

Clue 1: Code 4 8 2 : One digit right and in right position.

Clue 2: Code 4 1 6 : One digit right but wrongly placed.

  • Digit 4 cannot be in the 1st position in both clues and rightly placed in one and wrongly placed in the other.
  • Digit 4 must wrong.

In which clue digit 4 appears again?

Indeed, in Clue 3 digit 4 occurs and gives us two correct digits at one go.

Clue 3: Code 204 : Two digits right but wrongly placed.

  • Digits 0 and 2 are the correct digits.

Step 2: Identify digit placements for solution of the number lock riddle

Turn back to Clue 1 where digit 2 appears.

Clue 1: Code 4 8 2 : One digit right and in right position.

  • Correct digit 2 must be in the 3rd position in the code.

Focus on Clue 3 again to finalize the position of the correct digit 0.

Clue 3: Code 204 : Two digits right but wrongly placed.

3rd position already occupied by digit 2 and 2nd position is wrong for the other correct digit 0.

  • Correct digit 0 must be in the 1st position in the code.

Analyze the Clue 2 again as digit 1 is in the only available middle position.

Clue 2: Code 4 1 6 : One digit right but wrongly placed.

Either digit 1 or digit 6 is the remaining 3rd correct digit to occupy the 2nd position in the code.

Digit 1 is in the only free 2nd position and its placement description says, it is wrongly placed.

  • Digit 1 must be the incorrect digit and digit 6 the correct.
  • Digit 6 will occupy the 2nd position in the code.

Essentially, digit 1 is blocked out of positions in the code.

The code to open the number lock is 0 6 2.

Observation

Three clues to solve a 3 digit number lock code puzzle is the minimum. In this puzzle, the three clues are sufficient for solution.

But sometimes, to confuse, more clues not really needed, are included. An example of the same number lock riddle but with two additional clues this time:

3-digit-number-lock-puzzle-482-5-clues.png

Enjoy solving many more number lock puzzles. Click here.


More puzzles to solve

Easy to hard brain teasers with systematic solutions

Challenging brain teasers with solutions: Long list.

This is our complete list of specially chosen brain teasers (with step by step solutions) classified into categories that can be browsed separately.