Calculation: 1+2+3+...+98+99+98+...+3+2+1=how much.
计算：1+2+3+…+98+99+98+…+3+2+1=多少．
<gadget id="calculator">1 + 98</gadget>
<output>99</output>

<gadget id="calculator">98 / 2</gadget>
<output>49</output>

<gadget id="calculator">99 * 49 * 2</gadget>
<output>9_702</output>

<gadget id="calculator">9_702 + 99</gadget>
<output>9_801</output>

<result>9_801</result>