Definition. An even number is a number that is divisible by 2 without a remainder.
For example, 20 is an even number because it is divisible by 2 without a remainder:
20 : 2 = 10
Definition. An odd number is an odd number if it is divided by 2 and leaves a remainder of 1.
For example, 21 is odd because it is divided by 2 and leaves a remainder of 1:
21 : 2 = 10 (1 in the remainder)
How can you tell an even number from an odd number without having to divide by 2? Very simple. Even numbers are 0, 2, 4, 6, 8, and odd numbers are 1, 3, 5, 7, 9. If the number ends in an even number, then it is an even number. If the number ends in an odd number, then it is an odd number.
For example, the number 308 is even because it ends in an even number. The number 1024 is also even because it ends in an even number.
And the numbers 305 and 1027 are odd because they end in odd digits.
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