Three codes could be found in The Underground post on the Investigate Ingress blog.
[1] 4.1015659297.4.14081774942.4.12128529981.3.70842976927.3.68403149864.3.68403149864.3.75628575422.3.82586236554.4.06154810045.4.48140474656
[2] 354351152444523254434424131524442343152251
[3] 4ezi39uas96qxjv
Code #1
Observations
All numbers in the range of 4.x and 3.x
[hint]Searching for the first number should give you how to decode this[/hint]
Spoiler
Let’s start by splitting them up
4.1015659297
4.14081774942
4.12128529981
3.70842976927
3.68403149864
3.68403149864
3.75628575422
3.82586236554
4.06154810045
4.48140474656
Notice how we seem to have the prefix and suffix? 4.x would convert to letters and 3.x to numbers. Funny thing, if you search the first number on Google you get something about this numbers being the cubic root of 69. Let’s put everything to the power of 3 and round off to the closest decimal.
4.1015659297 
69 
4.14081774942 
71 
4.12128529981 
70 
3.70842976927 
51 
3.68403149864 
50 
3.68403149864 
50 
3.75628575422 
53 
3.82586236554 
56 
4.06154810045 
67 
4.48140474656 
90 
69 71 70 51 50 50 53 56 67
Convert decimal to Ascii
EGF32258CZ
Because we put everything to the power of 3 or cube, you now have the keyword.
egf32cube258cz
Code #2
Observations
All numbers in the range of 1 to 5. That’a a good indication.
[hint]What uses a 5×5 grid[/hint]
Spoiler
A range of numbers between 1 & 5 is a good hint that a Polybius square was used.

1 
2 
3 
4 
5 
1 
a 
b 
c 
d 
e 
2 
f 
g 
h 
j 
k 
3 
l 
m 
n 
o 
p 
4 
q 
r 
s 
t 
u 
5 
v 
w 
x 
y 
z 
Mapping out the coordinates should give you
psveitwmysticeithsegv
psv82mystic837gv
Code #3
Observations
Right amount of numbers for a passcode. You guessed it, same old, some old…
Spoiler
Make a 3×5 grid
4 
e 
z 
i 
3 
9 
u 
a 
s 
9 
6 
q 
x 
j 
v 
Read going right and up from the bottom left x
xjv96quasi394ez
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