16 12" x 12" tiles
*This presumes the given room size is exact and there are no cuts required. If there are cuts required for a toilet flange for example, best to allow for breakage. A general rule of thumb is to allow 10 - 15% waste for straightforward installs.
There are 3 tiles per foot, so 9 per square foot. 3 ft x 5 ft = 15 sq ft x 9 tiles per sq ft = 135 tiles
There are 9 (4X4) tiles in one square foot and you have 25 sq feet. Multiply 25 by 9 and the answer is 225.
270
16
54 4x4-inch tiles.
Assuming it's a 4x4 wall, 64 tiles
1080 will be your answer
You can fit nine 4x4 tiles in one squre foot (3 tiles wide by 3 tiles long). 56 square feet times 9 = 504. Add about 10% for cutting a/o waste (50 tiles) and you should buy around 550 tiles to complete the job. Good luck.
I wouldn't recommend it. Most wall tiles are very smooth and wouldn't have any grit for the thin-set to adhere to.
4*4 inch = 16 sq inches per tile. 124 sq feet = 124*12*12 = 17856 sq inches = 17856/16 = 1116 tiles, assuming there is no wastage.
Floor it across a median.
To the floor, you'll just have to stop at every gas station