A pile of logs has 15 layers, the top layer has 8 logs, and each lower layer has 1 more than the upper layer. How many logs are there in this pile?
一堆圆木共15层，最上面一层有8根，下面每层比上层多1根，这堆圆木共有多少根？
<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<gadget id="calculator">8 + 8 + 14</gadget>
<output>30</output>

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

<gadget id="calculator">30 * (15/2)</gadget>
<output>225</output>

<result>225</result>