Can't check the formula of 569+649=1218
不能验算569+649=1218的算式是多少
<gadget id="calculator">649 - 649</gadget>
<output>0</output>

<gadget id="calculator">569 + 0</gadget>
<output>569</output>

<gadget id="calculator">649 - 569 - 569</gadget>
<output>-489</output>

<gadget id="calculator">569 + (-489)</gadget>
<output>80</output>

<result>80</result>