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Coin with unreadable tracking code


terratin

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Argh! I bought four dinosaur/mammoth coins at a megaevent recently. The mammoth one, as I found out at home looks somewhat different in that the tracking code is hardly visible :( If you look at this example: clicky there's a smooth rectangle around the tracking code. That doesn't seem to be the case with my coin. I can just about read three numbers and guess a fourth. What now? I have no idea which of the sellers I bought the coin from, and I'm living on a different continent, in a place with rather unreliable post services anyway. I also contacted the producer, but no answer yet. What else is there left to do?

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Hate to ask a stupid question but have you tried a magnifying glass? Some of us old coots have been using them as standard equipment for a while 'coz that is not an uncommon problem. Another tip is to photograph the coin and blow it up to full resolution. Good luck.

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Very likely you'll hear something after the weekend. Many of the web sellers are closed weekends.

 

Also, as mentioned earlier if you haven't already done it, try numerous angles and lighting. Top, side, shadowed, angled, brighter than normal, etc. But with no flat surface for the code to be engraved, it could be a 'miss' on the total code.

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Try sidelighting with a good flashlight... and clean spectacles. :ph34r:

 

Yes, that's what I've been doing to decipher the three letters I can actually read, which unfortunately includes the first two, MA. I don't want to send those trackables traveling, but it annoys me that this one isn't perfect.

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Hate to ask a stupid question but have you tried a magnifying glass? Some of us old coots have been using them as standard equipment for a while 'coz that is not an uncommon problem. Another tip is to photograph the coin and blow it up to full resolution. Good luck.

 

Good idea, with a photo! I will try that.

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try a second person too. i had one where i thought i tried every combination of letters/numbers that look alike (5/6/G, 4/A, 8/B...) and couldn't figure it out. all i had was just a constant "This tracking number isn't in our system message". i was going to email the manufacturer at work and asked my wife to text me what she thought the number was. Ya i tried for an hour probably she got it first shot.

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Not sure I like this idea, s.f.g. I might accidentally activate some other people's coins by doing so. Or do they normally not have following tracking codes?

 

Plus, I'm not sure I actually want to activate that coin.

 

you can check your guesses using this link: www.geocaching.com/track/details.aspx?tracker=MAxxxx; just replace replace the xxxx with your guess.

 

The outcome page is one of those:

1) The Travel Bug you requested does not exist in the system. -> not your coin, because the code is not registered yet.

2) someone else's coin page -> not your coin

3) This Trackable (coin name) hasn't been activated.

3a) coin name and shown icon don't match your coin, e.g. there are probably some state based coins that have tracking codes starting with MA

3b) coin name and shown icon match -> maybe your coin

 

This is the math (using approximations):

There is a total of 923.521 possible codes starting with MA (31*31*31*31, since Groundspeak uses 31 letters for each digit). 30 of those have the same first three digits and differ in the last one, another 30 differ only in the third digit and so on.

120 out of those 923.521 codes differ in just one digit. What is the probability that one other coin happens to have such a code?

 

Let's assume your coin exists 500 times, therefore 499 other codes were registered for this production. To draw one of those 120 codes out of 923.521 has a probability of about 0.013%, a little bit less when the first code is drawn, a little bit more, if the last of the 499 other codes is drawn, because some are already taken. Since the Java Applet I used doesn't allow enough digits anyway I rounded up here to 0.02% what makes the result "worse".

 

Result: The probability that one or more codes of those 499 codes match yours in 3 digits is about 9.5%, according to a Binomial distribution with p=0.0002, n=500 and k>=1. (note: Binomial distribution is not correct because the probability p is not constant during all 500 generations, but growing. But the value of p is 50% too high anyway, because I rounded up before).

 

If you assume you got 2 digits wrong in your reading the numbers are not as good: The chances that no other code matches yours in two digits are only less than 5%.

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