Puzzleup 2016 (17) Seven - 拼圖

題目網址: http://www.puzzleup.com/2016/
http://www.puzzleup.com/2016/puzzle/?17
答題時限: 11月17日７ＰＭ－比賽結束（約12月14日）
加分時限: 11月17日７ＰＭ－11月23日６：５９ＰＭ

答對可得基本分１００分。答案可上傳５次，每改１次答案從基本分扣２０分。　
比賽期間內可隨時上傳答案，加分時限內答對第ｎ天加（６－ｎ）分　 　　 　　
另依題目的難易有額外加分（如有８０％的人這題答錯，答對者加８０分）　　

◆SEVEN

There is a number with digits appearing at most twice and all the numbers
formed by adjacent two digits are divisible by 7.

What can be the maximum value for this number?

Example:63563 is such a number (63, 35, 56 and 63 are divisible by 7)
but it is not the maximum.

有此一數，其每個數字至多出現兩次，且所有相鄰兩位數所形成的數皆可被 7 整除。

問此數最大為何？

例: 63563 為符合條件的一數 (63、35、56、63 皆可被 7 整除)，但並非最大。

--
'You've sort of made up for it tonight,' said Harry. 'Getting the
sword. Finishing the Horcrux. Saving my life.'
'That makes me sound a lot cooler then I was,' Ron mumbled.
'Stuff like that always sounds cooler then it really was,' said
Harry. 'I've been trying to tell you that for years.'
-- Harry Potter and the Deathly Hollows, P.308

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