天山04-28

[米琪]

Q28:
A school administrator will assign each student in a group of n students to one of m
classrooms. If 3 < m < 13 < n, is it possible to assign each of the n students to one of the
m classrooms so that each classroom has the same number of students assigned to it?
(1) It is possible to assign each of 3n students to one of m classrooms so that each
classroom has the same number of students assigned to it.
(2) It is possible to assign each of 13n students to one of m classrooms so that each
classroom has the same number of students assigned to it.


答案是 B 怎麼解出來的呢?

謝謝大家~~~

[StanleyHuang]

題目可以簡化成 問 n mod m = 0 ?? ( n mode m 表示 n除以m的餘數)

1) 3n mod m = 0 => 因為 m 也有可能是 3 的倍數，n mod m 不一定為 0
2) 13n mod m = 0 => 因為 m = 4...12，所以 m 不可能是13 的倍數。
所以當 13n mod m =0 時，可知 n mod m 也一定為 0
所以選 (B)

[米琪]

題目可以簡化成 問 n % m =0 ??
1) 3n%m = 0 => 因為 m 也有可能是 3 的倍數，n %m 不一定為 0
2) 13n%m = 0 => 因為 m = 4...12，所以 m 不可能是13 的倍數。
所以當 13n%m =0 時，可知 n%m 也一定為 0
所以選 (B)

請問一下 n % m =0 是什麼意思呢?
我看不懂符號耶

[StanleyHuang]

請問一下 n % m =0 是什麼意思呢?
我看不懂符號耶

慘~~我把算式當成程式在寫~~真是不好意思~~
% 是指取餘數，例如 5%3 就等於 2