How do three odd numbers add up to an even number**********

How do three odd numbers add up to an even number**********

Odd number can be expressed as 2n + 1, even number can be expressed as 2n, then the sum of three odd numbers can be expressed as (2n + 1) + (2n + 1) + (2n + 1) = 6N + 3 = 2 (3N + 1) + 1. If 3N + 1 is regarded as N, it is expressed as 2n + 1. So it must be odd number