There are 5 steel pipes, and each steel pipe is going to be sawn into 4 sections. It takes about 2 minutes to cut each section, and how many minutes will it take to saw all of them.
有5根钢管，打算把每根锯成4段，每锯开一段大约需要2分钟，全部锯完大约需要多少分钟．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">6 * 5</gadget>
<output>30</output>

<result>30</result>