new iron sheet mailbox was installed at the gate of Guangming Primary School. It is 50cm long, 30cm wide, and 68cm high. How many square centimeters of iron sheet are needed to make this mailbox?
光明小学门口装了一个新的铁皮邮箱，长50cm，宽30cm，高68cm，做这个邮箱至少需要多少平方厘米的铁皮？
<gadget id="calculator">50 * 30</gadget>
<output>1_500</output>

<gadget id="calculator">50 * 68</gadget>
<output>3_400</output>

<gadget id="calculator">30 * 68</gadget>
<output>2_040</output>

<gadget id="calculator">1_500 + 3_400 + 2_040</gadget>
<output>6_940</output>

<gadget id="calculator">6_940 * 2</gadget>
<output>13_880</output>

<result>13_880</result>