King's Maths department is located in the Strand building of King's Strand campus. Here is an overview map of King's Strand campus. The Strand building is shown in green.
To get to rooms numbed S4.* and S5.* in the maths department, enter the Strand building via the entrance on the Strand. Take the lift to level 4 or level 5 and follow the signs on the wall.
Finding your way around King's Strand campus is not that easy. There are two buildings joined together called the Strand building (which has modern architecture) and the King's building (which has Victorian architecture).
Levels in the Strand building have numbers such as S1.23 which means Strand building, level 1, room 23. Note that basement rooms have negative numbers such as S-1.23. There are also some mezzanine floors marked by U for upper and L for lower. To find a room such as K4U13, first find level K4 and then look for staircases to the upper and lower levels of that floor.
Levels in the King's building have numbers such as K1.23 which means Strand building, level 1, room 23. Note that basement rooms have negative numbers such as K-1.23.
Maps are not even available for most floors. You can find the official floor plans here but they are not easy to follow. I have produced the following combined floor plans of the Strand and King's building which should help you get your way around.