A 900 sq foot area will have a 30 ft side (Sqrt(900)=30) So given that 16 inches = 1.333 feet # tiles on edge = 30/1.333 = 22.5 22.5^2 = 507 tiles
1344. Each tile is a square foot.
The answer will depend on the depth to which the area is covered.
540 feet2
You would need 8.
4
A 900 sq foot area will have a 30 ft side (Sqrt(900)=30) So given that 16 inches = 1.333 feet # tiles on edge = 30/1.333 = 22.5 22.5^2 = 507 tiles
If you are willing to use offcuts to fill in spaces, mosaic-style, then 50 tiles will suffice. But you could require up to twice as many if you want a neat finish.
a 2x2 tile fills 4 square feet. 260/4=65 tiles.
1344. Each tile is a square foot.
Another 53.75 square feet of tile would be needed.
A 3x12 room is 36 square feet. This means that to fill the floor in the 3x12 room, it will take 36 tiles that are each 1 square foot (12x12) in size.
If the 210 square ft area is a convenient shape, or if offcuts can be used to fill up odd parts then 53 tiles will suffice.
The answer will depend on the depth to which the area is covered.
540 feet2
You would need 8.
26928 pebbles for the minimum depth.