Puzzleup 2016 (12) Last Digit - 拼圖

Table of Contents


題目網址: http://www.puzzleup.com/2016/
http://www.puzzleup.com/2016/puzzle/?12
答題時限: 10月13日7PM-比賽結束(約12月14日)
加分時限: 10月13日7PM-10月19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)  

◆LAST DIGIT

What is the last digit of the result of this addition operation?

以下和式的末位數字為何?

1 2 3 (10^100 - 1) (10^100)
1 + 2 + 3 + ... + (10^100 - 1) + (10^100)

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¯\_(ツ)_/¯

--
'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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