There is a cuboid fish tank in Xiao Ming’s house. The length measured from the inside is 20 cm, the width is 8 cm, and the height is 15 cm. How many square centimeters of glass is needed to make this cuboid fish tank? (There is no glass on the top of the fish tank)
小明家有一个长方体鱼缸，从里面测量长是20厘米，宽是8厘米，高是15厘米，制作这个长方体鱼缸，至少需要玻璃多少平方厘米？(鱼缸的上面没有玻璃)
<gadget id="calculator">50 * 40</gadget>
<output>2_000</output>

<gadget id="calculator">50 * 30</gadget>
<output>1_500</output>

<gadget id="calculator">40 * 30</gadget>
<output>1_200</output>

<gadget id="calculator">1_500 + 1_200</gadget>
<output>2_700</output>

<gadget id="calculator">2_700 * 2</gadget>
<output>5_400</output>

<gadget id="calculator">2_000 + 5_400</gadget>
<output>7_400</output>

<result>7_400</result>