How many square tiles, each with a side length of 25 cm, are needed to cover the floor of a room measuring 4 meters by 9 meters, if a 0.25 meter gap is left around the edges?

Explanation

To calculate the number of tiles required, first subtract the 0.25 m border from each side, reducing the effective floor dimensions to (4 - 0.5) m by (9 - 0.5) m, which equals 3.5 m by 8.5 m. Convert these dimensions to centimeters (350 cm by 850 cm). Each tile covers 25 cm by 25 cm. The number of tiles along the length is 350 / 25 = 14, and along the width is 850 / 25 = 34. Total tiles needed = 14 * 34 = 476.