Cut a round iron sheet with a diameter of 10 decimeters into two semicircles of equal size, what is the area of each semicircle?
把一块直径是10分米的圆铁皮，剪成大小相等的两个半圆片，每个半圆片的面积是多少．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">25 / 2</gadget>
<output>25/2 = around 12.5</output>

<gadget id="calculator">3.14 * (25/2)</gadget>
<output>39.25</output>

<result>39.25</result>