This is a viral so-called brain teaser where it mentions that the numeric lock is a three digit key. If we solve it using the hints you'll arrive at the answer 042, which is where I'm a little concerned, since I believed a three digit number mustn't start with zero. I understand the puzzle may've used a different definition of digit where it may simply have considered digits to be numeric numbers 0,1,..,9. What I want to know whether it's correct to do so. Thank you! Image link is here
Can a three digit number start with zero
puzzle
Best Answer
The typical base $10$ representation of numbers is frequently not unique though the problem is seen less often with integers. Are these numbers different: $1, 1.0, 1.00$? How about $.5, 0.5, 0.50$?
Similar, $042$ is an unusual way to write $42$ but it still the same number.
In some contexts, this unusual representation is common. Look at the odometer in a car. Mine currently says $099950$ so soon it won't start with a $0$ but it has for the last $18$ years. Numerical locks are another case in which this is common. It is also common with times in $24$ hour notation e.g. 09:30.