Cut a watermelon in half, the cut surface is exactly a circle with a diameter of 2 decimeters, then how many square decimeters the surface area of the watermelon increases after being cut.
将一个西瓜对半切开，切开的这个面正好是直径2分米的圆，那么西瓜被切开后表面积增加了多少平方分米．
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1 * 2</gadget>
<output>6.28</output>

<result>6.28</result>