Add 8 to a number, multiply by 8, subtract 8, and divide by 8. The result is 9. What is the number?
一个数加上8，再乘8，再减去8，再除以8，结果是9，这个数是多少．
<gadget id="calculator">8 * 9</gadget>
<output>72</output>

<gadget id="calculator">72 + 8</gadget>
<output>80</output>

<gadget id="calculator">80 / 8</gadget>
<output>10</output>

<gadget id="calculator">10 - 8</gadget>
<output>2</output>

<result>2</result>