There is a piece of wood, it takes 4 minutes to saw each time, and several minutes to saw into four pieces.
有一根木料，每锯开一次，要花4分钟，锯成四段要几分钟．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<result>12</result>