To find out how many tiles are required to cover the floor of a square bathroom, we need to calculate the area of the bathroom floor first. Given that the side of the square bathroom is 3 meters, we can use the formula for the area of a square:

Area of square = side x side

Substituting the given value of side in the formula, we get:

Area of bathroom floor = 3 meters x 3 meters = 9 square meters



Next, we need to find out the area of one tile. It is given that each tile is a square of side 20 cm. We can convert the side length to meters to use it in our calculation. 1 meter is equal to 100 centimeters, so the side length of one tile in meters is:

Side length of one tile = 20 cm / 100 = 0.2 meters

Using the formula for the area of a square, we can calculate the area of one tile as:

Area of one tile = 0.2 meters x 0.2 meters = 0.04 square meters



Now that we know the area of the bathroom floor and the area of one tile, we can find out how many tiles are required to cover the entire floor. We can do this by dividing the area of the bathroom floor by the area of one tile:

Number of tiles required = Area of bathroom floor / Area of one tile

Substituting the values we calculated earlier, we get:

Number of tiles required = 9 square meters / 0.04 square meters = 225 tiles

Therefore, we would need 225 tiles to cover the floor of a square bathroom of side 3 meters.