Close to the posted coordinates you will find an information kiosk. Use it to get the final.
N 49 07.ABC W 122 54.DEF
A = Briarwood Trail, first number
B = Pinewood - Canyon Trail, second number - first number
C = Gravity Bowl - Canyon Trail, first number
D = Pinewood - Canyon Trail, second number
E = Lower Trail, first number
F = Upper - Lower Trail, second number
A + B + C + D + E + F = 21