A multi for your enjoyment.
At stage 1 you will notice a six digit verticle number. To get the last three digits of the final for the North, use this formula:
A=3rd digit - 1st digit
B=5th digit
C=3rd digit
N 38 24.ABC
To get the last three digits for the West, use this formula:
D=3rd digit - 2nd digit
E=5th digit - 6th digit
F=3rd digit
W 121 27.DEF