The number of six digits is () A. 40B. 60C. 80D. 10

The number of six digits is () A. 40B. 60C. 80D. 10

If the number of single digits is even, if 2 is in the single digit, then 1 is in the ten digit, and there are a22a22 = 4. If 2 is not in the single digit, there are A12 · A12 · A22 · A22 = 16. If the number of single digits is even, there are 4 + 16 = 20 six digits. Similarly, if the number of single digits is odd, there are 20 six digits that meet the conditions, and the number of such six digits is 40

The number of six digits is ()
A. 40B. 60C. 80D. 10

If the number of single digits is even, if 2 is in the single digit, then 1 is in the ten digit, and there are a22a22 = 4. If 2 is not in the single digit, there are A12 · A12 · A22 · A22 = 16. If the number of single digits is even, there are 4 + 16 = 20 six digits. Similarly, if the number of single digits is odd, there are 20 six digits that meet the conditions, and the number of such six digits is 40

Use 1, 2, 3, 4, 5, 6 numbers to form a six digit number without repetition. It is required that the parity of any two adjacent numbers is different, so that the six digit number can be shared______ Answer with numbers

The first step is to arrange 1, 3 and 5, with a total of A33 = 6 permutations; the second step is to insert 2, 4 and 6 into the empty permutation, so that the space between two even numbers can not be empty. First, arrange the middle two spaces with two elements, and select one of the two ends to put the third element, with a total of 2a32 = 12 permutations; according to the principle of step multiplication and counting, there are 6 × 12 = 72 So the answer is: 72