Accomodation
When trying to find a suitable accomodation You may begin with
Booking.com
See this map for the location of Mathematical Department.
Here is a list of some hotels in the neighbourhood of Stockholm University:

• Best Western
• Elite Hotel Arcadia
  Stockholm University has a special agreement with Best Western and Arcadia hotels.
  The (fixed) price is 1197 SEK per night.
  Please notice that it might be cheaper to book these hotels via Booking.com if You book in advance.
• Scandic Park Hotel
• Hotel Oden
• Vanadis Hotel, (budget)
You may also look for some accomodation via Stockholm's official visitors guide

Visit Stockholm