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It’s really easy to see over a shoulder, and if you are able to deduce the buttons that were pressed, then there are only 24 possible combinations. This lock has no timeout for failures, and there is another public door nearby which means that people will sometimes be near when I’m putting in the code.
How is it only 24? What am I missing? 0-0-0-0 to 9-9-9-9, no?
This is where I got that number from, and it assumes that there are no repeated buttons.
https://socratic.org/questions/how-do-you-figure-out-the-number-of-combinations-in-4-digit-numbers
Ah, ok, so there's only 4 numbers to work with, and the code has to be a length of 4 as well? Can numbers not be repeated? It should be 4^4 I believe, because you can do 1-1-1-1, 1-1-1-2 etc.
Assuming the numbers go from 0 to 9 (those included) and can be repeated, it must be 10 * 10 * 10 * 10 = 10000 combinations :-)
Their assumption is that it is four digits long and the person knows which four digits but not the order.
Ah, ok. So it's not just trying all combinations. The numbers could be worn out from pressing over and over, for example.