There is a pile of logs piled up in a trapezoidal shape. There are 6 logs on the top layer and 10 logs on the bottom layer. There are 5 layers in total. How many logs are there in this pile?
有一堆圆木堆成梯形，最上面一层有6根，最下面一层有10根，一共堆了5层，这堆圆木共有多少根．
<gadget id="calculator">6 + 10</gadget>
<output>16</output>

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

<gadget id="calculator">16 * (5/2)</gadget>
<output>40</output>

<result>40</result>