pile of steel pipes, every two adjacent layers have a difference of 1, the uppermost layer is 2, and the bottom layer is 8, how many steel pipes are there in total?
一堆钢管，每相邻两层都相差1根，最上层2根，最下层8根，这堆钢管共多少根．
<gadget id="calculator">2 + 8</gadget>
<output>10</output>

<gadget id="calculator">8 - 2</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

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

<gadget id="calculator">10 * (7/2)</gadget>
<output>35</output>

<result>35</result>