2 sticks of 3 cm and 2 sticks of 1 cm are used to form a rectangle, what is its perimeter in cm?
用2根3厘米，2根1厘米的小棒围成一个长方形，它的周长是多少厘米．
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<result>8</result>