Divide a circle with a radius of 1 decimeter into several equal parts, cut them out and assemble them into an approximate rectangle. What is the perimeter of this rectangle in decimeters?
把一个半径是1分米的圆平均分成若干份，剪开拼成一个近似的长方形，这个长方形的周长是多少分米．
<gadget id="calculator">3.14 * 2 * 1</gadget>
<output>6.28</output>

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

<gadget id="calculator">6.28 + 2</gadget>
<output>8.28</output>

<result>8.28</result>