1月数学1-100单独讨论贴（题目到齐）有问题 看这里 不要再开新帖了

天蝎座1107

Or
r= things each one get

3*r+1=W

so r= (W-1)/3
But we know there is one remaining
so one person can get this extra one

so you get two people with (W-1)/3, one get (W-1)/3+1 or (W+2)/3

3*r+1=w多好理解啊。。。谢谢。发现数学讨论帖里有你好多高见，多多指教啊。

天蝎座1107

49（DS）7^M除以5的余数

1：M除以4余数为1
2：M除以3余数为2

7^M的个位数按照7，9，3，1的次序循环，7M除5的余数也按照2，4，3，1的次序循环。所以只要M按照4的倍数循环就可以。
1：M除以4余数为1，说明M=4N+1, 不管N等于几，7M 个位数始终为7，被5除后余数始终为2.
2：M除以3余数为2，7M的个位数不确定，所以余数也不确定。
答案是A

7的乘方的末尾不是7,9,3,1一直循环下去么，那条件1得末位是7，条件2得末位是9，条件1和条件2单独都可以的。选D

wangxiaoqing

M could be 5,8,11

3,9,7,1

unit digit of M^5 is 3
unit digit of M^8 is 1
unit digit of M^11 is 7

so can not determine

so B is not right

wangxiaoqing

I am talking about the exposed faces, and only exposed faces are painted


2个正方体叠一起: total of 12 faces; but you got three faces that can not be exposed to be painted.
2个正方体横过来: total of 12 faces; but you got four faces that can not be exposed to be painted.