I'd say 45 * 10^4
Total outcome:
9 *
10^5
Explanation:
9 is number of ways first digit can be selected(obviously, 0 cannot be the first number of the 6-digit number so there is only 9 possible choices)
10^5 is number of ways to select each of the remaining 5 digits
What you need now in order to have their sum being odd is:
E+E+E+E+E+O
E+E+E+O+O+O
E+O+O+O+O+O
As can be seen, you need either 1 odd, 3 odd or 5 odd numbers in order to have the sum being odd. However, the odd of having 1 even, 3 even or 5 even numbers is just the same. Therefore, probability of having odd/(total odd+even) is 1/2
Answer is 1/2*9*10^5 = 45*10^4