A six-digit number, rounded up to ten thousand digits, is about 500,000, which is 3900 greater than the original number. What is the original number?
一个六位数，四舍五入精确到万位约是50万，比原数大3900，原数是多少？
<gadget id="calculator">50 * 10_000</gadget>
<output>500_000</output>

<gadget id="calculator">500_000 - 3_900</gadget>
<output>496_100</output>

<result>496_100</result>