The length of a cuboid is 3dm, and the width is 20cm. If the height increases by 2dm, how much will the surface area increase by dm**2.
一个长方体的长是3dm，宽是20cm，若高增加2dm，表面积会增加多少dm**2．
<gadget id="calculator">20 / 10</gadget>
<output>2</output>

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

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

<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>