A batch of steel pipes is piled up in a trapezoidal shape. There are 5 steel pipes on the top layer, and the bottom layer is always 1 more than the upper layer. There are seven layers in total. How many steel pipes are there in this batch?
一批钢管堆成梯形，最上一层有5根，下边的一层总比上边的一层多1根共七层，这批钢管共几根？
<gadget id="calculator">5 + 1 + 1 + 1 + 1 + 1 + 1</gadget>
<output>11</output>

<gadget id="calculator">5 + 11</gadget>
<output>16</output>

<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">16 * (7/2)</gadget>
<output>56</output>

<result>56</result>