A batch of cement piles are transported from the construction site of the mobile building and piled up in a trapezoidal shape. There are 8 piles on the upper floor and 16 piles on the lower floor, making a total of 9 floors. How many piles are there in this batch of cement piles?
移动大楼建设工地运来一批水泥桩，堆成梯形，上层有8根，下层有16根，共9层，这批水泥桩有多少根．
<gadget id="calculator">8 + 16</gadget>
<output>24</output>

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

<gadget id="calculator">24 * (9/2)</gadget>
<output>108</output>

<result>108</result>