three digit number with even sum

We can fill the hundred's place in 9 ways (any digit from 1-9).

Ten's place in 10 ways (0-10)

The unit's digit can be however filled in only 5 ways as opposed to the usual 10 ways since it can be filled by either only even no.s or only odd no.s depending on whether the sum of the ten's place and the hundred's place digit is even or odd.

Hence no. of ways is 450.