There are a pile of steel pipes in a steel factory. There are 100 steel pipes in the bottom layer, and there are one less in each upper layer. There are 20 layers in this pile. How many steel pipes are there in this pile?
钢铁厂有一堆钢管，最下层有100根，每向上一层少一根，这样堆了20层，这堆钢管一共有多少根．
<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">100 - 19</gadget>
<output>81</output>

<gadget id="calculator">81 + 100</gadget>
<output>181</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">181 * 10</gadget>
<output>1_810</output>

<result>1_810</result>