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[数论] 2016!(!表示阶乘)最后一个非零尾数

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realnumber Posted at 2016-7-19 11:41:16 |Read mode
2016!(!表示阶乘)的结果中从右往左数第一个非0的数字是多少?

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 Author| realnumber Posted at 2016-7-19 12:40:01
Last edited by realnumber at 2016-7-19 12:58:00定义==表示两整数右边最后一个非零尾数相同,比如:710==45100==1.
那么$2016!==(尾数不是0)×(尾数恰好1个0)×(尾数2个0)×(尾数3个0)$
$2016!==((1×2×3×4×5×6×7×8×9)^{201}×1×2×3×4×5×6)×((1×2×3×4×5×6×7×8×9)^{20}×1)×(1×2×3×4×5×6×7×8×9)^2×(1000×2000)$
因为$1×2×3×4×5×6×7×8×9==8$
$2016!==8^{223}×2×2==6^{55}×8^3×4==8$


和程序得到不一样,哎~~程序得到的最后三位是704.
QQ截图20160719121023-9.png

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Tesla35 Posted at 2016-7-21 00:41:58
前几天刚看到有人总结了通法 tieba.baidu.com/p/4675746528

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kuing Posted at 2016-7-21 01:17:50
回复 3# Tesla35

585还逛贴吧

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Tesla35 Posted at 2016-7-21 01:24:48
回复 4# kuing

论坛不温不火,贴吧还是有点人气的。

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阿鲁 Posted at 2016-7-21 02:17:29
回复 5# Tesla35

但是水帖也不少

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isee Posted at 2016-7-21 11:29:23
回复  kuing

论坛不温不火,贴吧还是有点人气的。
Tesla35 发表于 2016-7-21 01:24
其实主要是数论太难了,没专门看过数论书的,基本是做不了这题的。

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isee Posted at 2016-7-21 11:30:19
前几天刚看到有人总结了通法
Tesla35 发表于 2016-7-21 00:41

    实际上,这数论中了也是有定论的。

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