Calculation: 1+2+3+4+...+48+49+50+49+48+...+4+3+2+1.
计算：1+2+3+4+…+48+49+50+49+48+…+4+3+2+1．
<gadget id="calculator">1 + 50</gadget>
<output>51</output>

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

<gadget id="calculator">51 * 25</gadget>
<output>1_275</output>

<gadget id="calculator">1_275 - 50</gadget>
<output>1_225</output>

<gadget id="calculator">1_275 + 1_225</gadget>
<output>2_500</output>

<result>2_500</result>