processing plant shipped a batch of steel pipes. Stack it into a trapezoidal shape, with 6 on the top and 14 on the bottom. Counting from top to bottom, there are 9 floors. How many steel pipes are there in total?
一个加工厂运来一批钢管．把它堆成梯形状，最上层有6根，最下层有14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>