The coordinates will take you to a signpole in the central park of Espoo.
The signs indicate your distance from many places (in kilometers).
A = Distance to Tapiola
B = Distance to Henttaa = Distance to Espoon Keskus - 4,7
C = Distance to Puolarmetsä = Distance to Henttaa + 0,2
Now proceed to
N 60°10,xxx'
E 24°43,yyy'
Where
xxx = 998-50*A-20*C
yyy = 101+50*A+14*C
Once there, look for a number in wood. Let the number be D.
Update 8th October, 2019
After 15 years in service the wooden pole was destroyed by a bunch of mushroom smoking smartasses. If you so wish, you may try to find it and value for D at 25 meters Northwest from its original position.
The metallic joints that attached pole to bedrock are still in place. Let their number be E.
The number of holes in all joints combined is F.
Final cache is at
N 60°11,aaa'
E 24°43,bbb'
Where
aaa = 40*B+6*E-1
bbb = 30*A*F+40*B+21*C-1
Round off the decimals and add an appropriate amount of zeros in front of the result where needed.
Don't delete final coordinates from your GPSr. You'll need those with Pentagram-5. In logbook there's also crucial clue for Pentagram-4.
The box is ½ litre Tupperware.
Links to other caches in this series:
Pentagram-2
Pentagram-3
Pentagram-4
Pentagram-5