Hollis is a town with a lot of conservation land. The Hollis Conservation Commission has a tiny (0.75 acre) parcel that is not well known and rarely visited. It is a triangular piece of land surrounded on two sides by Beaver Brook Association land and Route 130 on the north side. There is a small sign along Rt. 130 at the posted coordinates. From here you will have to jump a ditch and climb a hill.
The puzzle: figure out the three digit local telephone exchange for Hollis. Call this ABC.
DEF = ABC / 2.5
The final is at N 42° 44.ABC' W 71° 36.DEF'