Shortcut Trick
The side of the largest square tile is the HCF of the floor dimensions.
Side = HCF(525, 700) = 175 cm.
Number of tiles along length = 700 ÷ 175 = 4.
Number of tiles along breadth = 525 ÷ 175 = 3.
Total tiles required = 4 × 3 = 12.
∴ The correct answer is 12.
Alternate Method
Given: Dimensions of the rectangular floor are 700 cm and 525 cm.
Formula: Number of tiles = (Area of floor) ÷ (Area of one square tile), where tile side = HCF(Length, Breadth).
⇒ Prime factors of 700 = 22 × 52 × 7
⇒ Prime factors of 525 = 3 × 52 × 7
⇒ HCF (Side of tile) = 52 × 7 = 25 × 7 = 175 cm.
⇒ Area of floor = 700 × 525 = 3,67,500 cm2.
⇒ Area of one square tile = 175 × 175 = 30,625 cm2.
⇒ Number of tiles = 3,67,500 ÷ 30,625 = 12.
∴ The correct answer is 12.
Additional Information
HCF (Highest Common Factor)
HCF is the largest positive integer that divides each of the integers without a remainder. For tiling problems, the HCF of the dimensions gives the largest possible square tile size.
Area of Rectangle and Square
Area of rectangle = Length × Breadth. Area of square = side2. The number of objects required to cover an area is always Total Area ÷ Object Area.
Minimal Tiling Rule
To minimize the number of tiles used to cover a fixed rectangular area, the size of each tile must be maximized, which is why the HCF is calculated.