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Here are the even numbers.

2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, ... ,

and here are the odd numbers.

1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, ... ,

We see that a natural number is even if its one’s digit is

2, 4, 6, 8 or 0

A number is odd if its one’s digit is

1, 3, 5, 7 or 9

If the one’s digit of a number is 0, 2, 4, 6 or 8 then the number is divisible by 2.

Any number cba can be written as 100c + 10b + a

First two terms namely 100c, 10b are divisible by 2 because 100 and 10 are divisible by 2. So far as a is concerned, it must be divisible by 2 if the given number is divisible by 2. This is possible only when a = 0, 2, 4, 6 or 8.