A cuboid iron box is 20 cm long, 15 cm wide, and 10 cm high. How many square centimeters of iron sheet should be used to make this iron box?
一个长方体铁盒长20厘米，宽15厘米，高10厘米，做成这个铁盒至少用多少平方厘米的铁皮？
<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>