(1+2+3+4+...+99+100)-(2+4+6+8+...+96+98)=how much.
(1+2+3+4+…+99+100)-(2+4+6+8+…+96+98)=多少．
<gadget id="calculator">1 + 100</gadget>
<output>101</output>

<gadget id="calculator">100 / 2</gadget>
<output>50</output>

<gadget id="calculator">101 * 50</gadget>
<output>5_050</output>

<gadget id="calculator">2 + 98</gadget>
<output>100</output>

<gadget id="calculator">49 / 2</gadget>
<output>49/2 = around 24.5</output>

<gadget id="calculator">100 * (49/2)</gadget>
<output>2_450</output>

<gadget id="calculator">5_050 - 2_450</gadget>
<output>2_600</output>

<result>2_600</result>