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Five numbers 0,1,2,3,4 can be used to form three even numbers which are not allowed to repeat I know the answer is 30, and I want the process to be done in a combinatorial sequence
0 tail C (4,1) C (3,1) = 12
2 tails C (3,1) C (3,1) = 9
4 tails C (3,1) C (3,1) = 9
How many even four digit numbers without repeating numbers can be made up of five numbers: 0,1,2,3,4?
There are two cases
Bits are zero: 4 * 3 * 2 = 24
Bits not zero: 2 * 3 * 3 * 2 = 36
So there are 60
Five numbers 0, 1, 2, 3 and 4 can be used to form () even numbers without repeated numbers
Five even numbers: 4 * 3 * 2 * 1 + 2 * 2 * 3 * 2 * 1 = 48
The number of four even numbers composed of 1 223 45 is
First arrange a bit, the number of individual digits can be 2 or 4, and then select 3 numbers to rank in the other 3 digits, there are
2 × a (3,4) = 2 × (4 × 3 × 2) = 48 (species)
It can be composed of four numbers: 0, 1, 2 and 3______ Four even numbers with no number repetition
(1) When the number of digits is 0, there are six such four digits: 123013202130231203210;
(2) When the number of digits is 2, the four digits are 1032130231023012, 4 in total;
Total: 6 + 4 = 10
A: it can form 10 even four digit numbers without repeating numbers
So the answer is: 10
The six numbers 1, 2, 3, 4, 5, and 6 can form many six digits. Arrange them from large to small. What number is 365421
Just calculate how many numbers are greater than 365421
365421 is the largest number of 3 in the first place
Therefore, all numbers greater than 365421 are the numbers with the first place greater than 3
According to the principle of multiplication:
There are three possibilities in the first place (4,5,6), there are 5 possibilities left in 10000, 4 in 1000, 3 in 100, 2 in 10 and 1 in individual
3 × 5 × 4 × 3 × 2 × 1 = 360
5 421 are bigger than 3, 636
365421 is the 361st number
Of the six digits composed of numbers 1 and 2, there are exactly 3 consecutive digits. How many six digits are 1?
Among the six digits composed of numbers 1 and 2, there are exactly 3 consecutive digits and 12 six digits of 1
In the case of three ones: 111222211122221112222111;
The situation of four ones: 111212111221112111212211212111;
Five ones: 111211112111
How many different six digits are made up of six numbers: 1,2,2,3,3,3
31
The numbers 1,2,3,4,5,6,7,8,9 can form several six digits
If the number can be repeated, it is 9 to the sixth power, which is 531441 numbers
If it cannot be repeated, it is 9 * 8 * 7 * 6 * 5 * 4 = 60480 digits
How many six digits are there from 0 to 9?
There are 10 possibilities for ten, one hundred, one thousand, ten thousand, one hundred thousand,
There are nine possibilities in a million bits
So 10 ^ 5 * 9 = 900000
If different numbers are required, then 9 × 9 × 8 × 7 × 6 × 5 =
one hundred and thirty-six thousand and eighty
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