what even + odd number= an even number?

Answer 1

No such even and odd number exist.
In general we can express any even number as 2*n where n is some integer. Similarly, odd numbers can be expressed as 2*m+1 where m is some integer. So when we add an even number to an odd number we would get 2*n + 2*m+1. Which is 2*(m+n)+1, which is an odd number by definition.

Answer 2

Even + odd = odd
odd + odd = even
Even + even = even

even * even = even
even * odd = even
odd * odd = odd

Answer 3

actually ther is none