A rectangular piece of paper with a length of 31.4 cm and a width of 20 cm is made into a cylinder. What is the lateral area of the cylinder in square centimeters?
把一张长31.4厘米、宽20厘米的长方形纸片做成一个圆柱体，圆柱体的侧面积是多少平方厘米．
<gadget id="calculator">31.4 * 20</gadget>
<output>628</output>

<result>628</result>