Not sure how you came up with that number, but its not worth 4 cents, nor has it ever been worth close to that. Any value it can possibly have is numismatic or melt. Its absolutely worthless in exchange value. Its obsolete currency. In ~1993 Mexico devalued its peso 1000-1 and came out with the "New Peso." So essentially all pre-1993 (not 100% sure on that date but 1993 is very close if not correct) Mexican coinage has no exchange value whatsoever as I believe there was a time limit to exchange old pesos for New Pesos and that time period has long come and gone. Even if your coin could be exchanged, it'd now be worth .00005 New Pesos. As of today, there are 13.074 New Pesos in 1 U.S. dollar. According to my math, if you could somehow exchange these, 1,000,000 of them would be worth 3.8 New Pesos or ~$0.29. It would take over 34,000 of them to equal 1 U.S. cent.
I think there is a hyperinflation lesson in there somewhere.
Now to answer your question, I'm not sure what I'd do with it, but I'm never taking it back to the bank. While certainly no major crime, I would think that its technically illegal. Its absolutely worthless, so its no different than putting a slug or washer into a roll of coins IMO. For me its just a principle thing. If someone steals my car that does not give me the right to go steal someone else's car to make up for it. To me, this is exactly the same, albeit on a MUCH smaller scale. With that said, I see very little foreign coinage in my area. If I lived in a Northern state where Canadian coins circulated frequently, I very well might have a different outlook.
Really? I majored in math and came up with these numbers? I was on my first cup of coffee, but this is embarassing. My apologies. Obviously 20,000 of these would make a new peso which is worth about 7.65 U.S. cents.
