Bài 4: Trang 173 - sách giáo khoa (SGK) toán tiếng Anh lớp 4To tile a rectangular room, one uses a...

Therefore, 1000 tiles are required to cover the floor of the classroom.

To find out how many tiles are required, we need to divide the total area of the classroom floor (400,000 square centimeters) by the area of each tile (400 square centimeters). So, 400,000 / 400 = 1000 tiles.

Since each tile has an edge of 20cm, the area of each tile is 20cm x 20cm = 400 square centimeters.

Next, we need to convert the 40 square meters into square centimeters because the tile size is in centimeters. 1 square meter is equal to 10,000 square centimeters, so 40 square meters is equal to 400,000 square centimeters.

We need to calculate the area of the classroom floor first. The area of a rectangle is width x length, so in this case, it would be 5m x 8m = 40 square meters.