When the number begins with 4, then there are 4! =24 permutations for 2, 3, 5, 6
Half of them, or 12 would be even, and the other half or 12, odd.
When the number begins with 5, then there are 4! =24 permutations for 2, 3, 4, 6
3/4 x 24 =18 would be even, and 1/4 x 24 =6 would be odd.
When the number begins with 6, then there are 4! = 24 permutations for 2, 3, 4, 5
Half of them or 12 would be even, and the other half or 12 would be odd.
So, 24+24+24 =72 numbers over 40,000, and:
12+18+12 =42 would be even, and:
12 + 6+ 12=30 would be odd.
Just as Melody found !!