Forgot password?
 Register account
View 2109|Reply 7

[数论] 2016!(!表示阶乘)最后一个非零尾数

[Copy link]

413

Threads

1432

Posts

110K

Credits

Credits
11105

Show all posts

realnumber Posted 2016-7-19 11:41 |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?

413

Threads

1432

Posts

110K

Credits

Credits
11105

Show all posts

 Author| realnumber Posted 2016-7-19 12:40
Last edited by realnumber 2016-7-19 12:58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

67

Threads

407

Posts

3537

Credits

Credits
3537

Show all posts

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

682

Threads

110K

Posts

910K

Credits

Credits
90973
QQ

Show all posts

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

585还逛贴吧

67

Threads

407

Posts

3537

Credits

Credits
3537

Show all posts

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

论坛不温不火,贴吧还是有点人气的。

2

Threads

17

Posts

133

Credits

Credits
133

Show all posts

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

但是水帖也不少

768

Threads

4685

Posts

310K

Credits

Credits
35004

Show all posts

isee Posted 2016-7-21 11:29
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。

768

Threads

4685

Posts

310K

Credits

Credits
35004

Show all posts

isee Posted 2016-7-21 11:30
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。

Mobile version|Discuz Math Forum

2025-6-5 07:34 GMT+8

Powered by Discuz!

× Quick Reply To Top Edit