Definition: m＄n=m*mn*n, then 2＄4-4＄6-6＄8-8＄10-...-98＄100=how much.
定义：m＄n=m*m-n*n，则2＄4-4＄6-6＄8-8＄10-…-98＄100=多少．
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">4 - 16 - 16</gadget>
<output>-28</output>

<gadget id="calculator">100 * 100</gadget>
<output>10_000</output>

<gadget id="calculator">(-28) + 10_000</gadget>
<output>9_972</output>

<result>9_972</result>