Calculation: 1+2+3+...+50+49+...+2+1=how much.
计算：1+2+3+…+50+49+…+2+1=多少．
<gadget id="calculator">1 + 50</gadget>
<output>51</output>

<gadget id="calculator">50 / 2</gadget>
<output>25</output>

<gadget id="calculator">51 * 25 * 2</gadget>
<output>2_550</output>

<gadget id="calculator">2_550 - 50</gadget>
<output>2_500</output>

<result>2_500</result>