Probably none because a slab of granite would be measured in cubic feet.
220
54 meters squared
Multiply the length by the breadth. eg if slab is 2 ft by 3 ft then area of slab = 6 sq feet
A 9x9 foot slab 4 inches thick requires a minimum of 1 cubic yard. If you go to 6 inches thick you will need 1.5 cubic yards.
When talking about the area of a roof, remember that it is not the same as the square footage of the structure. For example a 20 x 30' building with a 12" overhang and a 4/12 pitch will have 736 sq ft of roof vs only 600 sq ft of slab. One square of shingles covers 100 square feet. 15 year shingles come 3 bundles to a square. 25 year come 4 bundles to a square.
21ft by 10ft
220
62 square feet.
300 square feet (25 x 12 = 300).
There are many materials that can come in different sizes like Granite, travertine, Porcelain and many more..
It depends on the thickness of slab. A yard of cement contains 9 cubic feet. Thus, it would cover 9 square feet if the slab was 1 foot thick. For a 4 inch thick slab, it would cover 3 times as much area, or 27 square feet.
15
The density of a substance is usually measured in weight units per volume (for example, per cubic foot), not per area. For a square foot... it would depend how thick the slab of granite is. That may vary between different manufacturers.
how many cubic feet in a yard of concret
15 feet x 15 feet = 225 square feet.
ju
How deep? Are you talking about dry mix weight or finished weight? Concrete weighs 150 pounds per cubic foot. So if you have a 6" slab, that's 150# for 2 square feet. For a 4" slab, the same amount will cover 3 square feet. For a 3" slab, 4 square feet. Concrete mix is commonly sold in 80 pound bags. The finished weight is the mix plus the water that gets chemically bound to it. There's a guide on the bag telling how many bags you need for a given area and thickness.