A cuboid iron box without a cover has a length of 40 cm, a width of 30 cm, and a height of 20 cm. If the inside and outside of this cuboid iron box are to be painted with paint, what is the area to be painted? (Iron sheet thickness is ignored)
一个无盖的长方体铁箱，长40厘米，宽30厘米，高20厘米，要把这个长方体的铁箱里面和外面都涂上油漆，涂油漆的面积是多少？(铁皮厚度忽略不计)
<gadget id="calculator">40 * 30</gadget>
<output>1_200</output>

<gadget id="calculator">40 * 20</gadget>
<output>800</output>

<gadget id="calculator">30 * 20</gadget>
<output>600</output>

<gadget id="calculator">800 + 600</gadget>
<output>1_400</output>

<gadget id="calculator">1_400 * 2</gadget>
<output>2_800</output>

<gadget id="calculator">1_200 + 2_800</gadget>
<output>4_000</output>

<gadget id="calculator">4_000 * 2</gadget>
<output>8_000</output>

<result>8_000</result>