A lawn is 156 meters long and 84 meters wide. If there is a wooden fence around it, do you know how many meters the wooden fence is at least?
一块草坪长156米，宽84米．如果在它的四周围上木栅栏，你知道至少围为多少米得木栅栏？
<gadget id="calculator">156 + 84</gadget>
<output>240</output>

<gadget id="calculator">240 * 2</gadget>
<output>480</output>

<result>480</result>