There are a pile of steel pipes in a steel factory. There are 18 steel pipes in the top layer, and one more in the lower layer than the upper layer. In this way, there are 5 layers of steel pipes. How many steel pipes are there in total in this pile?
钢铁厂有一堆钢管，最上层有18根，下一层比上一层多一根，这样堆了5层，这堆钢管一共有多少根．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">18 + 4</gadget>
<output>22</output>

<gadget id="calculator">18 + 22</gadget>
<output>40</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">40 * (5/2)</gadget>
<output>100</output>

<result>100</result>