609-708+306-108+202-198+497-100．
609-708+306-108+202-198+497-100．
<gadget id="calculator">609 - 708</gadget>
<output>-99</output>

<gadget id="calculator">306 - 108</gadget>
<output>198</output>

<gadget id="calculator">202 - 198</gadget>
<output>4</output>

<gadget id="calculator">497 - 100</gadget>
<output>397</output>

<gadget id="calculator">(-99) + 198 + 4 + 397</gadget>
<output>500</output>

<result>500</result>