piece of wood is 21 meters long, and it is sawn into several sections of 3 meters long, and each section takes 6 minutes to saw. How many minutes did it take to saw the log?
一根木料长21米，把它锯成3米长的几段，每锯一段用6分钟．锯完这根木料共用了多少分钟？
<gadget id="calculator">21 / 3</gadget>
<output>7</output>

<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">6 * 6</gadget>
<output>36</output>

<result>36</result>