Find the answer of the eighth grade in Mathematics It's a process

Find the answer of the eighth grade in Mathematics It's a process

The eighth grade mathematics dictionary

I hope you're not in the same class as me, eh~~~~~~

Among the four digit numbers without repetition, there are two odd digits, and how many are the four digit numbers of the two even digits?

First of all, use the permutation to select two even number positions, that is, the permutation of 2 out of 4 is 6; if the even number position is determined, the odd number position is also determined. Then the even number permutation may be 5 × 4, and the odd number permutation may also be 5 × 4. Because the above is carried out step by step, it will multiply to 2400. But because it must be four digits, so the first