(You can also look at the University's directions for visitors.)
Binghamton is located near the intersection of Interstate 81 and New York Higway 17. (Eventually, NY-17 will become Interstate 88.) The Binghamton University campus is most easily approached from Exit 70S of Highway 17. See the area map. Take Route 201 South about 2 miles, moving to the left lane as soon as you get on. Stay in the left lane to the end. At the end, you will be on the ramp to Route 434 East. Stay in the right lane on Route 434 and the first right turn available is the main entrance to Campus. Obtain a campus map at the visitors booth just inside the campus. The relevant section is the top central section.
The Department of Mathematical Sciences is in the Glenn G. Bartle Library Building. It is the large building just inside the top center of the main circular road on the somewhat outdated center section map. (There is no current replacement for that map. This more up to date campus parking map may be useful.) Note that for traditional reasons (perhaps because the main roads resemble the outline of a cranium and brain stem), the campus map is always presented with north on the bottom. A visitors, pay parking lot is just outside the circular road from the library building. You can also park in the ramp (labeled "parking garage") in the lower left of the center section map. Its fees are identical to the visitor parking lot (but it is farther from our department).
The Math Sciences Department is on the second floor of the northwest wing (remember the orientation of the map) of the library building. Since the building is large and complex, it is safest to walk to the entrance at the north (remember the orientation) end of the building. This is the entrance that is the farthest from the circular road and is near the winged teak statue (located at the wide blue rectangle representing a non-existent fountain on the somewhat outdated center section map). Turn to the right just inside the entrance and take the elevator to the second floor. You will be outside the main offices of the department: Library North (LN)-2200.