There are a pile of steel pipes on the construction site. The cross section is a trapezoid. It is known that there are 3 steel pipes in the uppermost layer and 16 steel pipes in the lowermost layer, and the lower layer has one more than the upper layer. How many steel pipes are there in total?
工地上有一堆钢管，横截面是一个梯形，已知最上面一层有3根，最下面一层有16根，并且下面一层都比上面一层多1根．这堆钢管共有多少根？
<gadget id="calculator">3 + 16</gadget>
<output>19</output>

<gadget id="calculator">16 - 3</gadget>
<output>13</output>

<gadget id="calculator">13 + 1</gadget>
<output>14</output>

<gadget id="calculator">14 / 2</gadget>
<output>7</output>

<gadget id="calculator">19 * 7</gadget>
<output>133</output>

<result>133</result>