There are some accommodation suggestions below.

College rooms

• If you have Cambridge connections, either as an alumnus or through friends, we encourage you to try getting guest rooms that way.
• Westminster College: very close to the Maths department. This is the only college likely to have a larger number of rooms available. The website looks a little out of date, but if you contact them, they will get back to you. As far as we've found out, they have 15 single bedrooms at £70.50 per night including breakfast, and 4 doubles for £102 per night per room, including breakfast.
• Cambridge Rooms: various College guest rooms. Currently nothing available for those dates, but you can check again after Easter, as I think Colleges put rooms on per term when they know availability. However, as this weekend is inside term time, there are most likely not going to be that many rooms available in any case. (Churchill College and Robinson College are both very close to the Maths department.)

Hotel suggestions

• Arundel House Hotel is one of the closest to the Maths department, and looks out over the river. Prices are reasonable (compared to other Cambridge City Centre hotels). It is also on the Citi4 bus route, which goes past the maths department.
• Lensfield Hotel is not too far out of the centre, and has reasonable prices.
• Best Western is not too far from the Maths department, close to the centre, and has reasonable prices for double rooms.
• For places like the Holiday Inn or the Premier Inn you would need a bike or car (or take taxis).

Bed and Breakfast

• Visit Cambridge: From what is currently available, probably Hobson House, Warkworth House and Lynwood House are within about 3/4h walking distance of the maths department.
• Cambridge Bed and Breakfasts: From what is currently available, probably Acorn Guest House, Warkworth House and The End House are withing 3/4h walking distance of the Maths department.
• booking.com
• etc.

General tip

If you can't find something within reasonable walking distance of the Maths department, you can try looking for something on the Uni4 bus route (mainly Hills Road south of the railway bridge). Uni4 and Citi4 are the only routes that go near the Maths department. The hotels listed below are also on other bus routes (Citi1 and Citi7) into the city centre (for evening meals/drinks).

Affordable(ish) hotels along Uni4 bus route

• Centennial Hotel currently lists £90 per night for a single, £100 per night for a twin or double.
• Cambridge Central Travelodge on Cambridge Leasure Park.
• Helen Hotel currently lists £51 per night for single, £68 per night for single occupancy in twin or double, £85 per night for twin or double.
• Royal Cambridge Hotel is quite close to the city centre, even walkable to the maths department, but currently lists £145 for standard single, £165 for standard double.