Question

Floor of a room is to be fitted with square marble tiles of the largest possible size. The size of the room is 10 m × 7 m. What should be the size of tiles required that has to be cut and how many such tiles are required

Answer 1

The area is 70 m^2 
Therefore, the largest square tile that we can fit is;
                            8.36660026534 by 8.36660026534This is the biggest possible square tile you can have for the room. 
You only need one.

I calculated this by square rooting the area of the room which i got by multiplying the dimensions you provided