There are three cubes of iron, their surface areas are 24 square centimeter, 54 square centimeter and 294 square centimeter respectively. Now we melt three pieces of iron into a big cube, and find the volume of this big cube
24 △ 6 = 4 (square centimeter), because 2 × 2 = 4, the edge length is 2 centimeter; 54 △ 6 = 9 (square centimeter), because 3 × 3 = 9, the edge length is 3 centimeter; 294 △ 6 = 49 (square centimeter), because 7 × 7 = 49, the edge length is 7 centimeter; large cube volume: 2 × 2 + 3 × 3 + 7 × 7 × 7