If a circle with a radius of 5dm is cut into an approximate rectangle, how much does the perimeter increase in dm?
把一个半径是5dm的圆剪拼成近似的长方形，周长增加了多少dm．
<gadget id="calculator">3.14 * 5 * 2</gadget>
<output>31.4</output>

<gadget id="calculator">31.4 / 2</gadget>
<output>15.7</output>

<gadget id="calculator">15.7 + 5</gadget>
<output>20.7</output>

<gadget id="calculator">20.7 * 2</gadget>
<output>41.4</output>

<gadget id="calculator">41.4 - 31.4</gadget>
<output>10</output>

<result>10</result>