And even if the number is randomly generated, many devices accept any string of digits that end with the correct four digits. Pressing "12345" actually tests both codes "1234" and "2345".
I'm sure there's an optimal sequence of keypresses that tests all 10000 codes in something like 30,000 keypresses rather than the naive 40,000.
I'm sure there's an optimal sequence of keypresses that tests all 10000 codes in something like 30,000 keypresses rather than the naive 40,000.