processing factory shipped a batch of steel pipes and piled them into a trapezoidal shape. There are 6 silver in the top layer and 14 in the bottom layer, and each layer is 1 more than the layer above it. There are 9 floors counting from top to bottom. How many steel pipes are there in this batch?
一个加工厂运来一批钢管，把它堆成梯形形状．最上层有6银，最下层有14根，每层都比它的上一层多1根．从上往下数共有9层，这批钢管共有多少根？
<gadget id="calculator">6 + 14</gadget>
<output>20</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">20 * (9/2)</gadget>
<output>90</output>

<result>90</result>