The calculation is actually easy. You only have to find to find out the pattern.
The cache is not at the coord in the heading. You will need to find the right move and fill in the missing numbers into these formula
N 27 4a.bcd
W 015 3e.fgh
a=F-3
b=P+5-K
c=H-1
d=S-(O*2)+6
e=C
f=(B-N)+2
g=I-(H*53)
h=N+N-7
