Given the rationale, provide a reasonable question and answer. Step-by-step reasoning process: First convert the length of the mural to inches: 15 feet * 12 inches / foot = 180 inches. Then convert the height of the mural to inches: 10 feet * 12 inches / foot = 120 inches. Then multiply the length and the height to find the total area of the mural: 180 inches * 120 inches = 21600 square inches. Since each tile is 1 square inch, this is also the number of tiles she needs.
 The question and answer:
Mary is building a mosaic for her school cafeteria's wall. It will be 10 feet tall and 15 feet long. Each tile she uses is 1 inch square. How many tiles will she need?
The answer is 21600