When I started swimming last May, I bought a digital lock for the locker room. I chose a lock with four digits rather than three. (Three-digit locks were $5 cheaper.) I knew that no one was going to open my lock in any case. I'm using it in a locker room where many people use no lock at all, even to protect their wallets. But ... I wanted never to waste a moment of anxiety over my stowed gear.
I initially set the combination to a familiar, memorable number. But over the months, I occasionally changed the number, for reasons that utterly escape me. When we came home from vacation in November, I realized I hadn't a clue what the number was. I had a completely useless lovely lock.
I bought a much cheaper and smaller 4-digit lock. This one has been a bitch too use. It barely fits, and in order to fit, it has bent just enough to make it hard to close. Last December I set about figuring out the combination of the original lock. I was pretty sure the first digit was 1, 4, 5, or 8. That meant testing at most 4,000 combinations. I figured, a few each day, I'll eventually get it. I started with the five thousands. (By the way, all the numbers in this story have been changed, to protect: me. I'm a touch paranoid about my lock.)
As I worked on the old lock, I began to lose some respect for it. My routine was to move a digit, tug; move a digit, tug. I noticed that I could tug a little further before meeting resistance, when the lock was set to any odd number, and it tugged even better if the last digit was a 3. When I got to 5533, my tug moved the handle a lot. I decided to try all the numbers ending in 33!
5633, 5733, and the lock opened!
What a relief, I can use my good lock again. But really, it's too easy to figure out the combination.