There are a pile of steel pipes. There are 6 steel pipes in the top layer and 20 steel pipes in the bottom layer. Each lower layer has one more than the upper layer. How many steel pipes are there in total?
有一堆钢管，最上层有6根，最下层20根，每下层都比上一层多一根，这堆钢管一共有多少．
<gadget id="calculator">6 + 20</gadget>
<output>26</output>

<gadget id="calculator">20 - 6</gadget>
<output>14</output>

<gadget id="calculator">14 + 1</gadget>
<output>15</output>

<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">26 * (15/2)</gadget>
<output>195</output>

<result>195</result>