Ask the expert to come in and help me guess what the right combination of 4 digit numbers is

6481 or 8461

Choose one out of 1357.

3 out of 2468.

Binding condition No1

There is one in the inference and one in 24, which means that 68 must be in the answer.

Binding condition NO

As you can see, 1 is included in the answer, while 2 is not.

So, the answer; is a number made up of .

Combined conditions, we can know that it must be in the first three places, so 1 is in the last place to combine conditions, because it is not in the last place, so four must be in the second place.

To sum up: the answer is 6841or8641

The method of arranging and selecting the landlord is incorrect, and the conditions are insufficient.

Probably 6481

If I add 0 to 9, I won't do it, my head will die!!

The correct one is 6481

The conditions are sufficient

Answer: 6481

1234 - 2 correct, but not in the right place.

1278 - 2 correct, but not in the right place.

1256 - 2 correct, but not in the right position.

5678 - 2 correct, but not in the right position.

It can be inferred that 1, 4, 6, 8 are included, and 1 is not in the 1st place, and 4 is not in the 4th place. 6 is not in 2,4 bits. 8 is not in 4 digits.

3456 - 1 is exactly right, 1 is wrong.

2468 - 1 is exactly right, 2 are out of place.

1357 - 1 correct, but not in the right place.

6 in 1 bit, 4 in 2 bit, 8 in 3 bit, 1 in 4 bit.

Due to insufficient conditions.

So there are multiple answers.

It's inconvenient to talk about them all here.

There are 24 combinations of four digits that make up four digitsCalculation: 4! =4*3*2*1=24.

Calculate how many combinations can be used to permutate combinations, e.g. 2345 can form 24 four-digit numbers, and these 24 four-digit numbers are:

Conceptual permutations and combinations are the most basic concepts of combinatorics. The so-called arrangement refers to taking a specified number of elements from a given number of elements and sorting them. Combination, on the other hand, refers to taking only a specified number of elements from a given number of elements, regardless of sorting.

The central issue of permutations and combinations is to study the total number of possible scenarios for a given required permutations and combinations. Permutations and combinations are closely related to classical probability theory.

There are 24 combinations of four numbers to form a four-digit number, and the calculation method: 4! =4*3*2*1=24.

Calculate how many combinations can be used for permutations.

e.g. 2345 can be made up of 24 four-digit numbers, and these 24 four-digit numbers are:

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Is there a 0 in these four numbers?

If there is zero, there are two cases.

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4 digits (without the number 0) can make up the four digits of unrepeated: a(4,4)=4 3 2 1=24;

4 digits (with the number 0) can make up the four digits of the unduplicated number: 3a(3,3)=3 3 2 1=18.

There are 24 permutations and combinations of 4 different numbers.

You can take 4 different numbers to permutate and combine, for example, 2, 3, 4, 5 these 4 different numbers, when 2 is in the highest digit there are 2345, 2354, 2435, 2453, 2534, 2543 and other 6 4-digit numbers, then 4 different numbers composed of 4 4 digits are as many as 4 6s, that is, 24.

But there is a permutation combination that is more special, that is, there are no 24 4-digit numbers arranged and combined with 3 different numbers and 0, because 0 cannot be ranked in the highest position.

Difference Between Permutations and Combines:

First, the meaning is different.

1. Arrange: stand or place in order.

2. Combination: The organization becomes a whole.

Example sentence: The combination of all these substitutions constitutes a system of making up for the defects.

Second, the focus is different.

1. Arrangement: From n different elements, take r non-repeating elements and arrange them in order, which is called taking r from n non-repeating arrangements.

Example sentence: The list of delegates is arranged in the order of the strokes of the surname.

2. Combination: From n different elements, take r non-repeating elements to form a subset, regardless of the order of their elements, which is called the unreassembled sum of r from n.

Example sentence: This combination on the stage is composed of five dazzling 28 beauties.

There are 24 combinations of four digits that make up four digitsCalculation: 4!

=4*3*2*1=24. Calculate how many combinations can be used to permutate combinations, e.g. 2345 can form 24 four-digit numbers, and these 24 four-digit numbers are:

Permutation of 4 numbers = 4! =4*3*2*1

Permutation of 5 numbers = 5! =5*4*3*2*1n number of permutations = n! =n*(n-1)*(n-2)*.1n！denotes the factorial of n.

Permutations and combinations. Pick three out of four numbers, a total of c(4,3)=4*3*2 3*2*1=4 combinations.

Permutation and combination problems are practical and interesting, but the question types are diverse and the ideas are flexible, so to solve the permutation and combination problem, the first family should carefully examine the question earlier, and figure out whether it is an arrangement problem, a combination problem or a combination of permutation and combination problems, if it is related to the order, it is a permutation problem, and if it is not related to the order, it is a combination problem; Second, it is necessary to grasp the essential characteristics of the problem and adopt reasonable and appropriate methods to deal with it.

Permutations and combinations. Pick three out of four numbers, a total of c(4,3)=4*3*2 3*2*1=4 combinations.

Permutation and combination problems are practical and interesting, but the question types are diverse and the ideas are flexible, so to solve the permutation and combination problem, the first family should carefully examine the question earlier, and figure out whether it is an arrangement problem, a combination problem or a combination of permutation and combination problems, if it is related to the order, it is a permutation problem, and if it is not related to the order, it is a combination problem; Second, it is necessary to grasp the essential characteristics of the problem and adopt reasonable and appropriate methods to deal with it.

There are 24 combinations of four digits that make up four digitsCalculation: 4!

=4*3*2*1=24. Calculations of the number of polypina combinations can be used without the use of permutations, e.g. 2345 can form 24 four-digit numbers, and these 24 four-digit numbers are:

Permutations and combinations are calculated as follows:

c(r,n) is the "combination", r is selected from n data, c(r,n)=n!/[r!(n-r)!]

a(r,n) is the "selection arrangement", from n data to select r, the big finch and the r data in the order of sorting, a(r,n)=n!/(n-r)!

a（3,2）=a（3,1）=（3x2x1）/1=6c（3,2）=c（3,1）=（3x2）/（2x1）=3