Use "+", "-", "*", "/" operation symbols to make the operation among 1, 2, 3, 4, 5, 6, 7, 8 equal to 8.
运用"+"、"-"、"*"、"/"运算符号使得1、2、3、4、5、6、7、8之间的运算等于8．
<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<gadget id="calculator">12 - 5</gadget>
<output>7</output>

<gadget id="calculator">6 - 7</gadget>
<output>-1</output>

<gadget id="calculator">8 - 9</gadget>
<output>-1</output>

<gadget id="calculator">1 + 2 + 7 + (-1) + (-1)</gadget>
<output>8</output>

<result>8</result>