There is a glass fish tank without a cover, which is 20 cm long, 15 cm wide, and 10 cm high. How many square centimeters of glass are needed to make such a pair of fish tanks?
有一种无盖的玻璃鱼缸，长20厘米，宽15厘米，高10厘米，做这样一对鱼缸需要多少平方厘米的玻璃？
<gadget id="calculator">300 + 200 + 150</gadget>
<output>650</output>

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

<gadget id="calculator">1_300 - 300</gadget>
<output>1_000</output>

<gadget id="calculator">1_000 * 2</gadget>
<output>2_000</output>

<result>2_000</result>