a: Take 3 digits from the 112th after the decimal.
b: Take 3 digits from the 91st after the decimal.
c: Take 3 digits from the 2209th after the decimal.
d: Take 3 digits from the 367th after the decimal.
e: Take 3 digits from the 55th after the decimal.
f: Take 3 digits from the 667th after the decimal.
The cache is at N a b.c W d e.f.
I just learned that some of you would feel more comfortable with 10s, 100s or maybe 5s rather than 3s. So I'm adding an alternative way to solve it, which might be a little easier for some of you.
Divide 1 by 9999800001. 1/9999800001=0.00000 00001 00002 00003 00004 00005 00006 00007...
a: Take 5 digits from the 186536th after the decimal.
b: Take 5 digits from the 180611th after the decimal.
c: Take 5 digits from the 91111th after the decimal.
You'll find the 15-digit coordinates by concatenating a, b and c.
Congratulations to TeamOttlet on FTS, and Rachell on FTF!
3/1/12: This puzzle was mentioned in the famous KPC series cache, Triskaidekaphobia (KPC2012)!
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