What is the mathmatical magic behind long distance phone cards?

I used long distance cards in the USA and now living in the Middle East, I use even more. Maybe 5 cards per week. Hundreds..... The general population here, being from other countries, uses just as many. They lie disposed, tossed on the streets by hundreds, after having been entered in their phone for credit. my questions is: although I understand there are millions, trillions of numeric combinations, how is it that there can be so many codes? The real question..haha is... as I have tried unsuccessfully to create a code to lucky get a match.. Is there a formula? How is it that a person could not enter a string of numbers and get lucky? What would the odds be that one day, I enter random numbers and catch some free minutes? My thought is that since indeed there are so many combinations, that the odds would increase not decrease.

What is the mathmatical magic behind long distance phone cards?
Mathematically, on the basis of probability, you can get lucky, but the odds are so slim, there virtually non existent. This is because the companies only put out 0.05% of the possible randomly generated combinations that are available, which can run into many trillions, so the more the number of digits in the code, the more the odds decrease. These days you only have to try a few times (three or four) to get barred, so they don't even give you a chance to get lucky. I really would like to know if there is anyone out there who has ever genuinely got lucky. Perhaps that should be your next question. GOOD LUCK!
Reply:if you 'got lucky' and guessed an unused card's number what would happen to the person who later bought the card? How would you feel if that person was you after you'd bought it and someone else had done the guessing?
Reply:%26lt;%26gt;Look at it this way: If every phone number in the world consisted of 10 digits, the total number of possibilities (n!) would be 3,628,800. 11 digits increases that to almost 40,000,000. When you look at 16 digit pin numbers, you have over 20 trillion combinations. Yes, eventually you will get "lucky" (the laws of chance and random possibility say you will), but it ain't gonna happen very often! Savor the victory (if and) when it comes!
Reply:I haven't used these cards for some time so can't remember how many digits there were to type.





I doubt that the number is just a random one. It is probable that there is a mathematical formula that is used and that some of the digits in the string are check digits. So choosing a number at random is very unlikely to work.





It is also probable that numbers are only valid for a limited time period (which may be several years).

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