Calculation: (100-1)+(99-2)+(98-3)+...+(52-49)+(51-50)=how much.
计算：(100-1)+(99-2)+(98-3)+…+(52-49)+(51-50)=多少．
<gadget id="calculator">99 + 1</gadget>
<output>100</output>

<gadget id="calculator">100 * 25</gadget>
<output>2_500</output>

<result>2_500</result>