If it takes 4 minutes to saw a piece of wood into 3 pieces, how many minutes will it take to saw it into 4 pieces?
把一根木头锯成3段用了4分钟，把它锯成4段，需要多少分钟．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

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

<result>6</result>