The old College Board tests were like that. To discourage guessing, in multiple choice tests with 5 options, they subtracted 1/5 of the wrong guesses instead of 1/4, leaving a slight mathematical advantage to guessing, if you assume that the options are equally distributed.
Cheers
Phil Hobbs
The infamous vending machines in the dorms at MIT were noted for jamming and not delivering the food... so many were rolled over and totally destroyed while I was a student there. ...Jim Thompson
Klingon?
That's called a "collision" if I understand their terminology correctly, and it took people a decade to find some even for MD5, so it's a very remote occurrence.
At one point I was a few dollars up on the Coke machine at the end of my aisle at IBM Watson. It had a dollar bill changer that would get jammed periodically. It turned out that when you power cycled it, part of its POST was to run the bill changer backwards, which would disgorge an indescribably crinkled dollar and make the machine work again.
Cost them a buck a time, but was much cheaper than a service call!
Cheers
Phil Hobbs
At school, we used to play pinball for a penny (it's relatively easy to trick a coin mechanism into accepting pennies *as* quarters).
After a few hours, we'd decide it was time to eat (or whatever) and would
*sell* the ~15 games we'd won (from that initial penny investment) and were no longer interested in playing to somebody nearby -- for 25c. Repeat this once or twice a day, seven days a week, etc.
That is actually a smart design feature if it keeps the thing running.
Someone in our physics department discovered you could get a free drink out of the students coffee machine by pouring LN2 into the coin slot.
The thing also had a weird quirk in that every drink combination was possible from the keypad - of which the most undrinkable was:
cold fizzy Bovril with extra milk and sugar
Not that much worse than hot flat Bovril!
Cheers
Phil Hobbs
A friend used #14 brass washers as dimes. One had to stick a piece of scotch tape over the hole to use them in parking meters and follow them with a few pennies to clear the mechanism so the meter maid couldn't see the washers.
There was also a way of tricking pay phones to take a penny, that was then returned.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required