There is a number that is divided by 7, added to 7, and finally subtracted from 7 to equal 7. What is this number?
有一个数，除以7，再加上7，最后减去7后正好等于7，这个数是多少．
<gadget id="calculator">7 - 7</gadget>
<output>0</output>

<gadget id="calculator">7 + 0</gadget>
<output>7</output>

<gadget id="calculator">7 * 7</gadget>
<output>49</output>

<result>49</result>