7456789-7456788+7456787-7456786+7456785-7456784=how many.
7456789-7456788+7456787-7456786+7456785-7456784=多少．
<gadget id="calculator">7_456_789 - 7_456_788</gadget>
<output>1</output>

<gadget id="calculator">7_456_787 - 7_456_786</gadget>
<output>1</output>

<gadget id="calculator">7_456_785 - 7_456_784</gadget>
<output>1</output>

<gadget id="calculator">1 + 1 + 1</gadget>
<output>3</output>

<result>3</result>