There is a pile of steel pipes on the construction site with a trapezoidal cross section. It is known that there are 2 steel pipes on the top layer and 12 steel pipes on the bottom layer.
工地上有一堆钢管，横截面是一个梯形，已知最上面一层有2根，最下面一层有12根，每层相差1根，这堆钢管共有多少根．
<gadget id="calculator">2 + 12</gadget>
<output>14</output>

<gadget id="calculator">12 - 2</gadget>
<output>10</output>

<gadget id="calculator">10 + 1</gadget>
<output>11</output>

<gadget id="calculator">11 / 2</gadget>
<output>11/2 = around 5.5</output>

<gadget id="calculator">14 * (11/2)</gadget>
<output>77</output>

<result>77</result>