There is a special mathematical operation symbol *, which makes the following equations true: 6*2=6+66, 5*4=5+55+555+5555. Please calculate 7*(2*1)=.
有一种特殊的数学运算符号*，使下列等式成立：6*2=6+66，5*4=5+55+555+5555．请计算7*(2*1)=．
<gadget id="calculator">7 + 77</gadget>
<output>84</output>

<result>84</result>