The main math office is Science Hall 236. This is located at Sweet Ave and Stewart St.
If you are coming to NMSU by air, the best way is to fly to the El Paso airport. There is a shuttle from the El Paso Airport to Las Cruces.
If you are driving from the south (El Paso) it is an easy trip up I-10 and take Exit 142 East University to Stewart Street.
If you are driving from the west (Deming or Tucson) it is I-10 to Exit 142 East University to Stewart Street.
If you are driving from the north (Albuquerque) it is I-25 to Exit 1 University Ave.
There is a good selection of nice hotels near the campus with several nice ones within a nice easy walk of 1 – 1.5 miles. The Courtyard by Marriott is the newest and is on the university campus. It is next to the Convention Center and within a very short walk there is a nice pub where you can eat. Others dining options nearby include mediterranean, asian, a nice pizza place, a sports bar and grill, as well as many others such as IHOP, Panda Express and so forth. The Hilton Garden Inn is also nice. Both hotels have a nice outdoor fire pit and swimming pool that can be a pretty enjoyable when most of the rest of the country is covered in snow.