A 12-meter-long wooden strip is sawed into 8 small sections. It takes 3 minutes to saw each section. How many minutes will it take to saw all the pieces?
将一根长12米的木条锯成了8小段，每锯下一段要用3分钟，全部锯完要用多少分钟．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

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

<result>21</result>