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In how many different ways can we use 0, 1, 2, 3, 4, to form a 4-digit number which must be a multiple of 3 (None of the five numbers can be used more than once)?
S={1, 2, 3, 4, 6}

T={1, 2, 3, 6, 8}

x is a number in set S, and y is a number in set T. What's the total number of all the different possible values of the product of x and y?
The hundreds digit and tens digit of a three-digit integer $$n$$ is odd and even,respectively. If the units digit is a number different from other two digits, what is the number of the possible value of $$n$$?
A 4-digit integer is formed by four integers selected from 0, 1, 2, 3 and the same figure can be repeatedly used. If the sum of the 4 digits is 3, how many different integers can be formed?
A 4-digit integer is formed by four integers selected from 0, 1, 2, 3, 4 and the same figure can be repeatedly used. If the sum of the 4 digits is 4, how many different integers can be formed?
Which of the following is a perfect square?
n is a positive even integer.

Quantity A

$$\frac{n!}{(n-2)!}$$

Quantity B

$$(2)(\frac{n}{2})!$$


A password is formed by 5 different letters (A, B, C, D, E), if no letter can be repeated in one password, how many different passwords can be formed?
How many 5-digit odd integers can be formed out of 3, 4, 6, 7, 9 such that each number is used for only once?
A father purchased theater tickets for 6 adjacent seats in the same row of seats for himself, his wife, and their 4 children. How many seating arrangements are possible if the father and mother sit in the 2 middle seats?
A students selects books for reading material randomly,and which of the following has exactly 10 different ways of selection?
Indicate all such statements.
S={1, 3, 5, 7,.............,397, 399}

Set S consists of the odd numbers from 1 to 399, inclusive. How many different ordered pairs $$(p, t)$$ can be formed, where $$p$$ and $$t$$ are numbers in S and $$p \lt t$$?

(Note: The sum of the integers from $$1$$ to $$n$$, inclusive, is given by the formula $$\frac{n(n+1)}{2}$$ for all positive integers $$n$$.)
There are four people, S, M, K and R. Some people should be selected from these four people to form a committee. The committee is required to have at least two people. How many different methods are there in total?
Two boys and two girls are selected from six boys and four girls. How many methods are there?
There are four books A, B, C, and D, how many arrangements if A and B must be next to each other?
If there are 6,840 different ways when promoting 3 out of 20 employees for three different positions, then in how many ways can 3 employees be selected out of 20 for three identical positions?
How many different 5-digit numbers can be formed by one "1",two "2",and two "5"?
Someone rearranges all the letters from the word "Mississippi"

Quantity A

The probability that all the same vowel letters are arranged together

Quantity B

The probability that all the same consonant letters are arranged together


There are 20 students in class with 10 girls and 10 boys. A teacher randomly selects some students and the first 6 students are all girls.

Quantity A

The probability that the 7th student is a girl

Quantity B

$$\frac{2}{7}$$


The room number is between 200 and 999, inclusive. If the double room has the unit digit of 3,what's the ratio of the number of double room to all the room?
Give your answer as a fraction.

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