The side area of a cylinder is expanded to get a square. It is known that the diameter of the bottom surface of the cylinder is 2 decimeters, and the volume of the cylinder is cubic decimeters The number obtained keeps the whole number

The side area of a cylinder is expanded to get a square. It is known that the diameter of the bottom surface of the cylinder is 2 decimeters, and the volume of the cylinder is cubic decimeters The number obtained keeps the whole number

2×3.14=6.28 3.14×(2/1)²×6.28=19.7192≈20