In a pile of steel pipes, each upper layer has one less steel pipe than the lower layer. It is known that there are 12 steel pipes in the lowest layer and 5 steel pipes in the uppermost layer. How many steel pipes are there in total in this pile?
一堆钢管每上一层比下层少1根，已知最下层有12根，最上层有5根，这堆钢管共有多少根．
<gadget id="calculator">5 + 12</gadget>
<output>17</output>

<gadget id="calculator">12 - 5</gadget>
<output>7</output>

<gadget id="calculator">7 + 1</gadget>
<output>8</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">17 * 4</gadget>
<output>68</output>

<result>68</result>