求解。。

你说过等我

1.How many 4-digit positive integers are there in which all 4 digits are even?答案：500




2.A certain right triangle has sides of length x, y, and z, where x < y < z.  If the area of this triangular region is 1, which of the following indicates all of the possible values of y ?
答案：y>√2


3.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：B


4.If each of the 12 teams participating in a certain tournament plays exactly one game with each of the other teams, how many games will be played?
答案：66

zliycdr

仅仅是路过。。

千位不可能是0 所以有4种可能2/4/6/8
而百位到个位都有5种可能0/2/4/6/8，于是4x5x5x5=500