Floor of a square room of side 10 m is to be completely covered with square tiles, each having length 50 cm. The smallest number of tiles needed is?

Area of square room = (10)² = 100 sq m
= 100 x (100)² sq cm
= 100 x 100 x 100 sq cm
Now, area of tiles = (50)² = 50 x 50 sq cm
∴ Number of tiles needed = (Area of square room) / (Area of tile)
= (100 x 100 x 100) / (50 x 50)
= 400
Hence, 400 tiles will be needed.