123456 is composed of 6 digits without repetition. There are only 2 even numbers adjacent to each other, and 1 cannot be placed at both ends How many are there
Permutation and combination
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- 1. Five cards are written with numbers 1, 2, 3, 4 and 5 respectively. If two of the five cards are randomly selected, the probability that the sum of the numbers on the two cards is odd is 0______ .
- 2. After adding + or - before the number 123456, are their algebra and s odd or even? Why? Add a sign between 1, 2, 3, 4, 5, 6, 7, 8, 9
- 3. There are 10 digital cards, at least a few cards out, in order to ensure that there are both odd and even numbers? Explain the principle of mathematics
- 4. Number 1, 2, 3, 4, 5, 6. Add a negative sign before some of them to make their sum 1. Please list all the formulas
- 5. In 123456.12, which numbers are preceded by a negative sign to make the sum of these numbers 0
- 6. 123456 these six numbers constitute countless repeated four digits, find out how many groups of numbers 1 is not in a single digit, 6 is not in a thousand digits
- 7. How many digits can a three digit password consist of?
- 8. In the experiment of "throwing regular hexahedron", if the six faces of regular hexahedron are marked with the numbers "1", "2", "3", "4", "5" and "6" respectively, if the number of tests increases, the frequency of the number "1" will change___ .
- 9. In the experiment of "throwing regular hexahedron", if the six faces of regular hexahedron are marked with the numbers "1", "2", "3", "4", "5" and "6" respectively, if the number of tests increases, the frequency of the number "1" will change___ .
- 10. Three dice, six faces are marked with the number 123456, if randomly cast these three, find the even probability of upward face, find the odd and even probability
- 11. 123456 = 1, fill in + 1, X in the brackets to make the equation hold
- 12. Fill in 123456 in o to form a triangle. Every three numbers add up to 10
- 13. Please fill in different rational numbers in the circle as shown in the figure, so that the sum of the three numbers on each line is zero? The top number is - 20
- 14. In the circle on the right, fill in the numbers that are not equal to each other, so that the sum of three numbers on each line is zero. How do you fill in? ( ) ( ) ( ) ( ) ( ) ( ) ----------------( -49) ( ) ( ) ( ) ( ) ( )
- 15. Use the six numbers 123456 to form a triangle so that each side is equal to 10
- 16. Use 123456 to form a six digit ABCDEF without repetition, so that ABC, BCD, CDE and def are multiples of 4, 5, 6 and 11, respectively
- 17. How many 4-digit numbers can be formed by 123456 without repetition and divisible by 3?
- 18. How many quadruple digits can 123456 make up
- 19. The number of six digits is () A. 40B. 60C. 80D. 10
- 20. A small cube block is marked with six numbers 1, 2, 3, 4, 5 and 6 on its six faces. How many different situations can we see at most on one or several faces of the cube from different angles?