4. (5 points) A rectangular prism, if its height increases by 2 cm, it becomes a cube, and the surface area increases by 56 square cm. The original volume of this rectangular prism is $\qquad$ cubic cm.
【Solution】Solution: The area of the added 1 face: $56 \div 4=14$ (square centimeters);
Length (width) of the rectangular prism: $14 \div 2=7$ (centimeters);
Height of the rectangular prism: $7-2=5$ (centimeters);
Volume: $7 \times 7 \times 5=245$ (cubic centimeters);
Answer: The original volume of the rectangular prism is 245 cubic centimeters.
Therefore, the answer is: 245.