If it takes 4 minutes to saw a piece of wood into two pieces, how many minutes will it take to saw it into 5 pieces?
把一根木头锯成两段要用4分钟，如果锯成5段要用多少分钟．
<gadget id="calculator">2 - 1</gadget>
<output>1</output>

<gadget id="calculator">4 / 1</gadget>
<output>4</output>

<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<result>16</result>