A steel pipe is sawn into 8 sections, each sawing takes 3 minutes, how many minutes will it take to complete the sawing?
一根钢管，锯成8段，每锯一次要3分钟，共需几分钟锯完？
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

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

<result>21</result>