Xiaoying's student number in the class is a two-digit number, which is larger than 24 and smaller than 30: it is 7 times the same number, what is Xiaoying's student number.
小英在班级的学号是一个两位数，它比24大，比30小：它还是一个数的7倍，小英的学号是多少．
<gadget id="calculator">7 * 4</gadget>
<output>28</output>

<result>28</result>