The Ford Expedition SUV has a combination lock feature that allows one to unlock the vehicle and obtain access to its interior even without a key. There are five buttons on the driver's door marked "1-2", "3-4", "5-6", "7-8", and "9-0", and the code consists of a sequence of five of these buttons yielding 5^5 = 3125 possible code sequences. It is quite possible to enter one code sequence each second, meaning the entire set of code sequences can be exhausted in 52 minutes. In fact, since on average one would only need to try about half the codes before finding the correct one, the average time would be less than one half hour. There are no built in obstacles to this kind of brute force method - the vehicle unlocks as soon as the correct code is entered, regardless of how many incorrect codes have been entered previously or by what length of time they are separated. And just think, if it had been designed with ten buttons instead of five OR with just two extra digits, it would take more than 24 hours.

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