The confusion begins with this definition a person might give of “prime”: a prime number is a positive whole number that is only divisible by 1 and itself. The number 1 is divisible by 1, and it’s divisible by itself. But itself and 1 are not two distinct factors. Excluding 1 from the primes smooths that out.

Proof: The definition of a prime number is a positive integer that has exactly two distinct divisors. Since the divisors of 2 are 1 and 2, there are exactly two distinct divisors, so 2 is prime. In fact, the only reason why most even numbers are composite is that they are divisible by 2 (a prime) by definition.

The first five prime numbers: 2, 3, 5, 7 and 11. A prime number is an integer, or whole number, that has only two factors — 1 and itself. Put another way, a prime number can be divided evenly only by 1 and by itself. However, 6 is not a prime number, because it can be divided evenly by 2 or 3.

Of course yes. Negative numbers can be odd or even. It’s very easy answer if you know the definitions of odd and even numbers. Integers which are multiples of 2, are even numbers.

0

So what is it – odd, even or neither? For mathematicians the answer is easy: zero is an even number. Because any number that can be divided by two to create another whole number is even.

All the numbers ending with 0,2,4,6 and 8 are even numbers. For example, numbers such as 14, 26, 32, 40 and 88 are even numbers. If we divide a number into two groups with an equal number of elements in each, then the number is an even number. In the case of odd numbers, we get a remainder of 1 while grouping.

The first 20 odd natural numbers are given by : 1,3,5,7,9……,37,39. Put all the values in the formula, Therefore,The sum of first 20 odd natural numbers is 400.

Proof of Sum of Odd Numbers

1. Sum of first odd number = 1.
2. Sum of first two odd numbers = 1 + 3 = 4 (4 = 2 x 2).
3. Sum of first three odd numbers = 1 + 3 + 5 = 9 (9 = 3 x 3).
4. Sum of first four odd numbers = 1 + 3 + 5 + 7 = 16 (16 = 4 x 4).

The number series 1, 3, 5, 7, 9, . . . . , 199. Therefore, 10000 is the sum of first 100 odd numbers.

Sum of First Ten Even numbers