16
54 4x4-inch tiles.
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.
I wouldn't recommend it. Most wall tiles are very smooth and wouldn't have any grit for the thin-set to adhere to.
There are alot of variables to consider when bidding a job like this. Material costs can vary greatly, depending on the style of the tiles. A good labor price for me per square foot is $1.25 for 2X2 $.85 for 2X4 and $.75 for 4X4 tiles but you also have to consider joist height compared to drop height and how cut up it is for extra rooms $15 set up per additional room.
There are 9 (4X4) tiles in one square foot and you have 25 sq feet. Multiply 25 by 9 and the answer is 225.
1080 will be your answer
270
16
54 4x4-inch tiles.
Assuming it's a 4x4 wall, 64 tiles
You cannot have an area of 120 ft. An area must be measured in square units, such as square feet. The answer will be different if the area is 120 ft by 1 ft wide or 10 ft wide or 10 miles wide!
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.
1080
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
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.
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.