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From one to six, every four numbers are combined. How many combinations are there How? Or what do you think? It's important to me
Do you mean 1234 and 1324 as one or two?
There are 15 combinations in one count
Count two, then 360 combinations
Also, can four numbers be repeated? For example, 1111, 1122, etc?
What can be repeated is the 1296 kinds mentioned above
Use the method of permutation and combination I forgot what grade the course was
If you haven't learned it, think like this:
The first situation: list it if you are not afraid of trouble
The second situation: a total of six numbers are selected. The number of thousand digits is selected as one from six, and the number of hundred digits is taken out as one from five. Similarly, the ten digit number is one out of four, and the single digit is one out of three, so the result is 6 * 5 * 4 * 3 = 360
The third case: there are six choices for the number in each position, that is, 6 * 6 * 6 * 6 = 1296
How many permutation methods are there?
9x9x9x9
There are five numbers in the range of 1 - 55, but the numbers are not repeated in each arrangement It's five numbers from 1 to 55. There are several ways to choose It's like five 11，33，44，55，23 If it's 11, 33, 44, 22, 11, it doesn't work.
In fact, we don't put back the extraction. We take 5 out of 55 numbers. In the first step, there are 55 numbers to choose from, 55 kinds to choose from, 54 kinds to choose from in the second step, 53 kinds to choose in the third step, 52 kinds in the fourth step, and 51 kinds in the fifth step, so there are 55 * 54 * 53 * 52 * 51 = 417451320
Help me to calculate a problem, from 0 to 9, 10 numbers in any way, but can only use 4 digits at a time. There are several kinds of permutation ways, and the numbers can be repeated!
10*10*10*10=10000
4 to 8 random combination, each number to use, how many kinds of arrangement? What are the respective? Now! It's OK to tell them what they are
That is to put a number first, and then put it after the difficulty. The second one can be put in the front and back positions by multiplying 2, and the third number can be put in the front, middle and rear with 3. The analogy is 1 * 2 * 3 * 4 * 5 * 6 * 7 * 8, and it is necessary to match the selection probability of the number after the difficulty
0,1,2,3,4,5,6,7,8,9 can be composed of several different four digit numbers and write them out 0,1,2,3,4,5,6,7,8,9 can be composed of several different four digits, and they can be written out one by one
9 * 9 * 8 * 7 kinds
There are 9 choices when the thousand digits cannot be zero
There are nine options for using up one hundred, ten digits, and nine digits left
Ten digits are the same as 8
There are 7 choices for single digits
How many four digits can be made up of two 3's, 1's and 2's?
There are 12 in total, 3312 / 3213 / 3123 / 3231 / 3321 / 3132 / 2133 / 2331 / 2313 / 1233 / 1323 / 1332
How many 8-digit numbers (2736) can be used to make up of 8 numbers without repetition and four even numbers connected together? (2736)
(5 * 4 * 3 * 2 * 1) * (4 * 3 * 2 * 1) - (3 * 2 * 1) * (4 * 3 * 2 * 1) = 2736, you can ask me if you don't know anything
The sum of two four digits composed of 1,2,3,4,5,6,7,9 is 10000. There are several permutations Make up two four digit numbers with eight number cards of 1,2,3,4,5,6,7,9, and make their sum be 10000. How many can you write?
4329+5671
4321+5679
4379+5621
4371+5629
4731+5269
4769+5231
Too many. You can find the rules
It can only be 1 and 9 at the end
It should be 6 × 4 × 2 = 48
Add "+" or "-" before the numbers 2, 3, 4, 5, 6, 7, 8, 9 to make their sum 10. How can you think of several ways?
-5 + 6 + 7 + 8 + 9 = 10 + 2 + 3 + 3 + 4 + 5 + 7 + 8 + 9 = 10 + 2 + 3 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 10 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 10 + 2 + 3 + 4 + 4 + 5 + 6 + 7 + 7 + 8 + 9 + 9 = 10 + 2 + 3 + 4 + 4 + 5 + 6 + 7 + 8 + 8 + 9 = 10 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 10 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 10 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 9 = 10 + 2 + 3 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 9 + 9 + 9 + 9 + 9 + 9 + 9 5 + 6 + 7-8-9 = 10 train of thought: 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = (2 + 9) * 8 /
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