A lace is 8 meters long. A picture frame is 2 meters long and 1 meter wide. Use lace around the frame for a week, how much is left.
一条花边长8米．一个镜框长2米，宽1米．用花边绕镜框一周，还剩多少．
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">8 - 6</gadget>
<output>2</output>

<result>2</result>