Original sentence: A tea room may have a floor area as small as 1.5 tatami mats or as large as 10 mats or more; 4.5 mats is generally considered the ideal in modern tea rooms
Edited sentence: A tea room may have a floor area as small as 1.75 tatami mats (one full tatami mat for the guests plus a tatami mat called a daime (台目), approximately 3/4 the length of a full tatami mat, for the portable brazier (furo) or sunken hearth (ro) to be situated and the host to sit and prepare the tea); or as large as 10 tatami mats or more; 4.5 mats is generally considered the ideal in modern tea rooms