My car which was made in 1997 has a factory CD player installed. If the stereo ever loses power then you need to enter the security code to use the CD player again. The system was installed to stop thieves from just ripping out the stereo to sell, as the system was once worth much more than the $20 it would go for these days.
The CD player has a funny way of getting you to input the 4 digit code. You basically have to press numbers 1 through 4 the appropriate amount of times to increment each of the 4 numbers to get your code.
So for my code, which is 6104 (please don’t steal my stereo) would logically have me pressing the 1 digit six times, 2 once, 3 zero times and 4 four times. Or at least I thought! Turns out you need to press the number 10 times to get to 0, otherwise it doesn’t register.
I wasted a good 5 minutes figuring that out! Odd!