A piece of wood is cut into 8 sections, each section takes 3 minutes, how many minutes did it take in total?
一根木头截成8段，每截一段用3分钟，一共用了多少分钟．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<result>21</result>