Why is the sum of two odd numbers even?

Answer 1

-- The first odd number is some even number plus an extra ' 1 '.

-- The second odd number is some even number plus an extra ' 1 '.

-- Add them. You get (an even number) + (an even number) + ( 2 ).

That's an even number.

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Another mind-bending , brain-busting way to look at it :

-- The first odd number is some even number plus an extra ' 1 '.

-- The second odd number is some even number minus ' 1 '.

-- Add them. You get (an even number) + (an even number) + ( [1 - 1] or zero ).

That's an even number.