Crack the Lock
Read the puzzle
A lock takes a 3-digit code. Clues: 578 has one digit right and in the right place, and one digit right but in the wrong place. 132 has one digit right and in the right place. 215 has no correct digits. 672 has one digit right but in the wrong place. Which 3-digit code opens the lock?
Which 3-digit code opens the lock?
738
3 sits in the middle, 8 stays last, 7 goes first.
How to solve it
Start with the clue that rules things out. 215 has nothing right, so 2, 1 and 5 are not in the code.
That leaves only 3 from 132, and it is in the right place: 3 is the middle digit.
In 578, the 5 is out, so 7 and 8 share the two marks. 7 cannot be in the right place, because the middle is 3, so 7 is misplaced and 8 is right, in last place. 7 then goes first.
Check 672: 7 is correct but misplaced; 6 and 2 are out. The code is 738.
Learn the method: Crack the Lock Riddle: Which 3-Digit Code Opens It? Answer: 738
