After dividing a circle with a diameter of 4 decimeters into two semicircles, what is the circumference of each semicircle?
把一个直径是4分米的圆分成两个半圆后，每个半圆周长多少分米．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

<gadget id="calculator">6.28 + 4</gadget>
<output>10.28</output>

<result>10.28</result>