Adding two "0"s at the end of a four-digit number becomes a six-digit number. The difference between the six-digit number and the four-digit number is 562221. What is the original four-digit number?
一个四位数的末尾添上两个"0"，就成了一个六位数，这个六位数与四位数的差是562221，原来的四位数是多少？
<gadget id="calculator">100 - 1</gadget>
<output>99</output>

<gadget id="calculator">562_221 / 99</gadget>
<output>5_679</output>

<result>5_679</result>