九岁小孩的一道算术题

牛二买刀

用2，5，11，17四个数字得出37.
每个数字只能用一次。

自己没想出答案，狗狗找不到答案，bing也找不到答案。只有到胡同来找了。

牛二买刀

找到答案了，子女教育的一个网友给了答案：

（17×5-11）/2

google

K，9岁小孩的算术题，把偶们屁挨着地都难住了

牛二买刀

K，9岁小孩的算术题，把偶们屁挨着地都难住了
google 发表于 2010-1-17 20:01

虽然是九岁小孩的题，但毕竟是数学系的教授给孩子出的题，还是有点难度的。
还有一道题是：
用5，5，5，1得出24。这个我自己想出来了。

dxzhu

It is too difficult for 9 year old child.

seafood

虽然是九岁小孩的题，但毕竟是数学系的教授给孩子出的题，还是有点难度的。
还有一道题是：
用5，5，5，1得出24。这个我自己想出来了。
牛二买刀 发表于 2010-1-17 20:16

答案是5x5-1^5吗？9岁小孩学过幂了？

牛二买刀

6# seafood


没学过的，给他们讲讲，不就算学过啦。

碧海潮生

Suppose we have N companies, and we want to eventually merge them into one big company. How many ways are there to merge?

牛二买刀

Suppose we have N companies, and we want to eventually merge them into one big company. How many ways are there to merge?
碧海潮生 发表于 2010-1-18 02:07

Full permutation?
N!

碧海潮生

Full permutation?
N!
牛二买刀 发表于 2010-1-18 02:37

If N=2, there is only 1 way. right?

xiaoshitou

(5-1/5)*5

cherryxia

答案是5x5-1^5吗？9岁小孩学过幂了？
seafood 发表于 2010-1-17 21:24

用分数就可以了，5*（5-1/5）=24

牛二买刀

If N=2, there is only 1 way. right?
碧海潮生 发表于 2010-1-18 03:29

Then need a restriction:

N<=2, result = 1;
N>2, result = N!

But I think the answer should be N! even with N =2, because A bought B is different from B bought A.

slihull

u guys are so good at math...

coexist

happylux

Where is 子女教育网? Are these questions for US kids/China kids?

牛二买刀

16# happylux


ZinNvJiaoYu is in Wenxue city.

These questions are from a math hobby team which my daughter joined.
The team is majorly for early middle school. My daughter just go there for some fun.