Accomodation in a hotel can be booked via the website of the Göttingen tourist office. Since the booking robot might give you hotels in the outskirts of Göttingen, you should make sure that the address in fact is Göttingen (but not "Adelebsen" or "Ebergötzen" and the like). Price per night starts at some 50 Euro per night and goes up to virtually infinity. The following hotels charge a price at the lower end of this interval:
The Leinehotel and Hotel Novostar are other options.
Some of the participants and lecturers will stay at the Hotel Kasseler Hof. For the precise location, click on "Lage/Anreise" and then on "Grösserer Kartenausschnitt bei Klick" just below the map.
Another option might be the youth hostel in Göttingen. Reservation can be made through Hostelling International, too.
University Guest House
Unfortunately fully booked - no accomocation available.
A description of travel possibilities to the Mathematics Institute can be found here.
WiFi and internet access will be available.
General information about Göttingen (including cafes, bars and shopping) can be found in the Gö-guide.