There is a piece of wood that is 8 meters long, and it needs to be sawed into 8 sections. It takes 3 minutes to saw each section. How many minutes did it take in total?
有一根木材长8米，要把他锯成8段，每锯一段要用3分钟，共锯了多少分钟．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

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

<result>21</result>