# Gcxxxx

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with only 4 places, the alphabet and 11 digits...how much longer can this waypoint description last before exhaustion.?

with only 4 places, the alphabet and 11 digits...how much longer can this waypoint description last before exhaustion.?

Another year or two or so. Last I hear TPTB were just going to add another character to it so we will virtually never run out.

please be more precise, and authorative to quell a raging argument

Edited by hannieIII

with only 4 places, the alphabet and 11 digits...how much longer can this waypoint description last before exhaustion.?

Well, at a guess, that would be 4 raised to the power of 36, which is around 450 trillion possible combinations. I say 36 because I'm not sure what the 11th digit you're referring to is. In any case, we won't run out soon.

with only 4 places, the alphabet and 11 digits...how much longer can this waypoint description last before exhaustion.?

Well, at a guess, that would be 4 raised to the power of 36, which is around 450 trillion possible combinations. I say 36 because I'm not sure what the 11th digit you're referring to is. In any case, we won't run out soon.

I'm a lurker, but I had to jump in here. It would be 36 to the 4th power, or 1,679,616.

with only 4 places, the alphabet and 11 digits...how much longer can this waypoint description last before exhaustion.?

Well, at a guess, that would be 4 raised to the power of 36, which is around 450 trillion possible combinations. I say 36 because I'm not sure what the 11th digit you're referring to is. In any case, we won't run out soon.

I'm a lurker, but I had to jump in here. It would be 36 to the 4th power, or 1,679,616.

Did I do that backwards? That explains a lot.

I guess we'll have to wait for Adrenalynn

Yep, 36^4 = 1,679,616 as it stands. I've seen geocaches that only had GCxxxx (I'm pretty sure), which opens up an additional character for the 4th slot (NOTHING), so 37 ^ 4 = 1,874,161. Don't know how far back it goes are far as the number of characters. Add an extra character (GCxxxxx) and it's 36^5 = 60,466,176. Or make it case sensitive with the existing 4 (GCxxxx) and you've got 62 ^ 4 = 14,776,336 (and a lot of confusion to boot!) Do both (62 ^ 5) and get 916,132,832 (plus confusion)

Are there REALLY near one and a half million geocaches out there?

Yep, 36^4 = 1,679,616 as it stands. I've seen geocaches that only had GCxxxx (I'm pretty sure), which opens up an additional character for the 4th slot (NOTHING), so 37 ^ 4 = 1,874,161. Don't know how far back it goes are far as the number of characters. Add an extra character (GCxxxxx) and it's 36^5 = 60,466,176. Or make it case sensitive with the existing 4 (GCxxxx) and you've got 62 ^ 4 = 14,776,336 (and a lot of confusion to boot!) Do both (62 ^ 5) and get 916,132,832 (plus confusion)

Are there REALLY near one and a half million geocaches out there?

I thought I had nothing to do.

I might be losing this argument, so would any other tries or existing valid ones please display the answer/s in exponential format , which my students haven't learned yet. My job is at stake

Also there are only 10 digits

Edited by hannieIII

I think it's 36*35*34*33,,whatever that is in exponential

I think it's 36*35*34*33,,whatever that is in exponential

It's 36*35*34*33 if you can't repeat a digit. If repetition is allowed (which it is), it's 36^4.

My understanding is that waypoints begin with "GC" for geocache. Early caches had 1 digit after this, then 2, 3 and now 4. I have found caches from 2001 with only 3 digits after the GC.

If that is the case, then with 4 digits there are a total of 1,727,604 caches that can be added. This would include caches that were submitted, but rejected and archived caches.

My guess is that we will move to "GC" plus a 5 digit suffix soon, allowing 62,193,780 total caches. Then extended again to 6 digits allowing 2,238,976,116 caches. This will then be the limit that some GPSr's can handle for waypoint names - but this is some way off.

When the length is increased to 7 digits, every possible spot on earth (subject to .1 mile restriction) will have a cache, plus 3 old, archived ones.

A couple of the posts got the math right, but the details wrong. It isn't base 36; the letter "O", for example, was excluded because it looks like a zero. The valid characters are 0123456789ABCDEFGHJKMNPQRTVWXYZ

http://forums.Groundspeak.com/GC/index.php...14entry368814

Describes the scheme. (That post is what I used in the code in GPSBabel before the "the great 65535 rollover" and it's worked fine.)

There are also a number of selective exclusions of possible GC code combinations due to the four letter words they would form. Because of that subjective bit of editing, the answer is not an exact mathematical equation (well, it could be but there would be some variable that would need to be subtracted from the equation to represent outlawed GC names)

Also, the original GC system was done a bit differently at first, where the location of the cache was part of GC number, such as 1=Oregon, 2=Washington, etc... So in that regard, the geocaches with a GCXX format didnt use all the available possibilities either.

OTher than individually counting all of these exceptions to the rule, coming up with a number of caches that will be used before the GCXXXX format is exhausted will only be an approximate number, rahter than an exact number.

Actually the number can be calculated quite precisely if you follow the link that RobertLipe posted.

By far, the biggest approximation is guessing how many of the waypoint numbers will be wasted on duplicate caches, abandoned mistakes, test caches and caches that are never published.

Actually the number can be calculated quite precisely if you follow the link that RobertLipe posted.

I've got a little online calculator that converts from waypoint to cache number and vice versa. As long as TPTB don't change their plans for the future, it will work for caches beyond GCZZZZ.

Edited by fizzymagic

I might be losing this argument, so would any other tries or existing valid ones please display the answer/s in exponential format , which my students haven't learned yet. My job is at stake

Also there are only 10 digits

ok, so here is the methodology in lehman terms. Say you have 4 dice each with 6 sides. If you grab all 4 dice at once and roll them at the same time, how many possible combinations do you have? Since every dice has 6 sides each die has 6 possible outcomes every time it is rolled. So the total number of possible outcomes is the sum of the possible outcomes (6) raised to the power of the number of dice (4). In our case it is 6^4=1296.

Apply this to the GCxxxx and we have 35^4=1,500,625 (note: there are only 35 possible outcomes so zero and the letter O would not get confused)

Note: this method only works when a character can appear in more than one spot at one time. for example: GCHHTY the "H" appears twice. If you can only use each character 1 time then you must use permutations rule which would look like this for geocaching (35!)/(35-4)!=1,256,640 note: the "!" is explained below.

I hope this clears it up for you.

I think it's 36*35*34*33,,whatever that is in exponential

The pattern you have described is known as the factorial function and is denoted by "!". So in this instance the pattern would be denoted 36! and would be equal to 371,993,326,789,901,217,467,999,448,150,835,200,000,000, unfortunately this is not the correct method for listing all possible outcomes.

Edited by tyberium

only 1,111,419 * left then , hardley doomed then are we?

*This number will be wrong now

please be more precise, and authorative to quell a raging argument

If you need more exact numbers: Using some advanced algorithms from an MIT AI laboratory, run on an advanced superconducting supercomputer owned by the largest non-Western spy agency in the world, into which our brokers have hacked, our calculations show that the current labeling system, at the current rate of growth of the sport, will last until 3:14 PM PST on January 12, 2007. Vitili multivariant regression variance is +/- 3 days, Snyder computed error is +/- 18 minutes with a Snellett confidence factor of 44.881882.

Also, the original GC system was done a bit differently at first, where the location of the cache was part of GC number, such as 1=Oregon, 2=Washington, etc... So in that regard, the geocaches with a GCXX format didnt use all the available possibilities either.

I don't think that's correct.

They were added to the system by state, but the state of origin was never PART of the GC code. I've got a sampling in an offline database where I track some information, and here's the ones that I've got where the sequential ID is <250

SEQ - ST - MMM DD YYYY - Waypoint

005 - WA - May 07 2000 - GC5

008 - WA - May 28 2000 - GC8

013 - WA - Jun 21 2000 - GCD

029 - GA - Jun 03 2000 - GC1D

040 - IL - May 13 2000 - GC28

041 - IL - Jun 03 2000 - GC29

042 - IL - Jun 08 2000 - GC2A

045 - IL - Jun 08 2001 - GC2D

047 - IL - Jun 19 2000 - GC2F

101 - IL - Sep 27 2000 - GC65

118 - GA - Oct 01 2000 - GC76

137 - GA - Oct 15 2000 - GC89

146 - WA - Oct 22 2000 - GC92

153 - IL - Oct 28 2000 - GC99

167 - IL - Nov 05 2000 - GCA7

182 - GA - Nov 13 2000 - GCB6

184 - IN - Nov 17 2000 - GCB8

218 - IL - Dec 09 2000 - GCDA

237 - AZ - Dec 17 2000 - GCED

I can't see any state pattern in the states.

I don't see a pattern in that list either, but to Markwell my reference, I was going by this post. It seems it was only the first few that applies to and a better system was in place well before they reached 250 caches.

with only 4 places, the alphabet and 11 digits...how much longer can this waypoint description last before exhaustion.?

Is that how many more caches or how much more time?

Just playing around - using Fizzy's calculator and a smattering of my own caches and placement dates - I came up with this graph - charts the growth of the useage of the numbers.

Assumed zero on May 3, 2000 - My first placement was 12/25/2001 - so no data in between (on the graph anyway)

Edited by StarBrand

I don't see a pattern in that list either, but to Markwell my reference, I was going by this post. It seems it was only the first few that applies to and a better system was in place well before they reached 250 caches.

While caches are all posted now in the order received, the first ~50 were organized by state and are all out of order by date.

Just as a point of clarification, it says that the first ~50 were organized by state, but it doesn't say that the waypoints had any state indicators in the name.

Of the ones that didn't have an "error" in the system

04 - GC4 - WA

05 - GC5 - WA

06 - GC6 - WA

07 - GC7 - WA

08 - GC8 - WA

09 - GC9 - WA

11 - GCB - WA

13 - GCD - WA

15 - GCF - OR

16 - GC10 - OR

So the Washington ones were entered first, and then Oregon, but you can't tell ANYTHING about the state from the GC code.

OK I've made my point, I'm done

My understanding is that waypoints begin with "GC" for geocache. Early caches had 1 digit after this, then 2, 3 and now 4. I have found caches from 2001 with only 3 digits after the GC.

If that is the case, then with 4 digits there are a total of 1,727,604 caches that can be added. This would include caches that were submitted, but rejected and archived caches.

My guess is that we will move to "GC" plus a 5 digit suffix soon, allowing 62,193,780 total caches. Then extended again to 6 digits allowing 2,238,976,116 caches. This will then be the limit that some GPSr's can handle for waypoint names - but this is some way off.

When the length is increased to 7 digits, every possible spot on earth (subject to .1 mile restriction) will have a cache, plus 3 old, archived ones.

That's kind of crazy to think about. So theoretically, even the oceans would have caches every .1 mile.

1,679,616 caches can have four digits.

with StarBrand's graph, assuming it is correct, I think we have two or three years before we need a fifth digit.

with StarBrand's graph, assuming it is correct, I think we have two or three years before we need a fifth digit.

Nope. We'll probably run out early next year.

GCZZZZ is cache number 512400. As of today, we are at around GCVR00, which is cache number 386510, leaving us only about 126000 caches to go before a fifth character is required.

I've occasionally posted about this in a thread showing the growth of geocaching; I will update the numbers tonight. IIRC, my original prediction, made sometime in 2004, was that we would need the fifth digit around May or June of 2007. However, the growth of caches has accelerated in the last 6 months or so above the long-term trend, so it will happen sooner.

I think it's 36*35*34*33,whatever that is in exponential

The pattern you have described is known as the factorial function and is denoted by "!". So in this instance the pattern would be denoted 36! and would be equal to 371,993,326,789,901,217,467,999,448,150,835,200,000,000, unfortunately this is not the correct method for listing all possible outcomes.

Although we aren't using factorials for the correct answer, 36! is wrong too. 36*35*34*33 = (36!)/(32!).

The correct mathematical formula for a 4 digit code with 36 possibilities is 36^4. I ignored the fact that O is removed, since _ appears to have been used for the earliest caches. This of course ignores the codes were never used.

The correct mathematical formula for a 4 digit code with 36 possibilities is 36^4. I ignored the fact that O is removed, since _ appears to have been used for the earliest caches. This of course ignores the codes were never used.

I'm sorry.

I've tried to be helpful and not make any snarky comments. But this is getting ridiculous.

Have you people bothered to look at anything posted on this subject before? Have you even bothered to read this thread? This thread is hardly the first discussion of these issues, which are very well understood!

No, the waypoints are not coded using 35 or 36 symbols. It's in base 31. Remember that number: 31.

In addition, all caches up to GCFFFF were encoded as hexadecimal numbers.

Robertlipe posted a link to the official description of the coding scheme earlier in this thread that you can use to convert from one to another. I posted a link to a Web page that will do the conversion for you. Please take the time to look at those before posting incorrect information.

That is all.

Is there any limit to how many incorrect answers can be be given to this question?

Edited: Yeah, what fizzymagic said about what I said. :-)

Edited by robertlipe

I have to add my \$0.02 in here. Fizzymagic and robertlipe know what they are talking about. Some people have noted that the letter "O" was not used. It is not the only one. For example the letter "L" is not used either. Look at the list that robertlipe posted earlier. Not only is it base 31, but some combinations that would result in four letter words that some people might find objectionable were also disallowed. The number that fizzymagic gave a few posts ago is the official number. While I have not read all of the linked thread, I would assume that the same letters are not being used with the seven digit codes as well. I'm also sure that the same care was taken with possible five letter words that was used with the four letter words. With that given there will NOT be a simple mathematical answer. Use fizzymagic's calculator. Believe me, it works correctly.

End of story.

Edit for spelling

Edited by WeightMan

I found my original prediction about when the would run out of 4-character codes. I made it in November of 2004, and I predicted June of 2007. Here it is!

I am now guessing late November of this year. Should we start a pool?

OK - here is my official guess - sometime on October 30th, 2006

Predicitng a slight acceleration as we approach the end of 4 place codes......

Edited by StarBrand

Is there any limit to how many incorrect answers can be be given to this question?

I'm sure fizzy could work up a formula for that too!

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