To be fair (I know you were only making a theoretical example) if you have a bathroom exactly 3.60 meters across, you won't anyway fit in it 12 x 30 cm tiles, n

To be fair (I know you were only making a theoretical example) if you have a bathroom exactly 3.60 meters across, you won't anyway fit in it 12 x 30 cm tiles, nor 6 x 60 cm ones without cutting one because of joints between tiles and thickness of the tiles. As a matter of fact in a 12 feet scenario 12 x 30.48 cm = 365.76 cm it is actually likely that you will be able to fit 12 x 30 cm tiles without cuts (but not 6 x 60 cm ones, unless you put them with very wide joints).