You must know the story of "Young Gauss" quick calculation! So what is the result of 1+2+3+4+…+999
你一定知道"少年高斯"速算的故事吧！那么1+2+3+4+…+999的结果是多少
<gadget id="calculator">1 + 999</gadget>
<output>1_000</output>

<gadget id="calculator">999 / 2</gadget>
<output>999/2 = around 499.5</output>

<gadget id="calculator">1_000 * (999/2)</gadget>
<output>499_500</output>

<result>499_500</result>