There is a strange three-digit number, which is exactly divisible by 7 after subtracting 7, exactly divisible by 8 after subtracting 8, and exactly divisible by 9 after subtracting 9. Guess what the three-digit number is.
有一个奇怪的三位数，减去7后正好被7整除，减去8后正好被8整除，减去9后正好被9整除．你猜猜这个三位数是多少．
<gadget id="calculator">7 * 8 * 9</gadget>
<output>504</output>

<result>504</result>