An area of rectangular floor with dimensions 90 cm and 40 cm is to be paved with square tiles of side 20 cm. How many such tiles will be required ?

Answer

To find out how many square tiles are required to pave a rectangular floor, we will follow these steps:

### Step 1: Calculate the area of the rectangular floor.
The area of a rectangle can be calculated using the formula:
\[ \text{Area} = \text{Length} \times \text{Breadth} \]

Given:
- Length (L) = 90 cm
- Breadth (B) = 40 cm

Calculating the area:
\[ \text{Area} = 90 \, \text{cm} \times 40 \, \text{cm} = 3600 \, \text{cm}^2 \]

### Step 2: Calculate the area of one square tile.
The area of a square can be calculated using the formula:
\[ \text{Area} = \text{Side}^2 \]

Given:
- Side of the square tile = 20 cm

Calculating the area:
\[ \text{Area} = 20 \, \text{cm} \times 20 \, \text{cm} = 400 \, \text{cm}^2 \]

### Step 3: Calculate the number of tiles required.
To find the number of tiles needed, we divide the area of the rectangular floor by the area of one square tile:
\[ \text{Number of tiles} = \frac{\text{Area of rectangular floor}}{\text{Area of one square tile}} \]

Calculating the number of tiles:
\[ \text{Number of tiles} = \frac{3600 \, \text{cm}^2}{400 \, \text{cm}^2} = 9 \]

### Final Answer:
Therefore, the number of square tiles required is **9**.

---