A piece of wood is sawn into 4 pieces. If it takes 3 minutes to saw each time, how many minutes will it take to finish all sawing.
一根木料要锯成4段．如果每锯一次要花3分钟，全部锯完要多少分钟．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<result>9</result>