It is obvious to make a cuboid carton with a length of 20cm, a width of 15cm and a height of 10cm. How many square centimeters of cardboard is needed to make such a carton?
明明要做一个长方体的纸盒，长20cm、宽15cm、高10cm，做这样一个纸盒至少需要多少平方厘米的硬纸板？
<gadget id="calculator">20 * 15</gadget>
<output>300</output>

<gadget id="calculator">20 * 10</gadget>
<output>200</output>

<gadget id="calculator">15 * 10</gadget>
<output>150</output>

<gadget id="calculator">300 + 200 + 150</gadget>
<output>650</output>

<gadget id="calculator">650 * 2</gadget>
<output>1_300</output>

<result>1_300</result>