Explanation: A prime number can have only 1 and itself as factors. Any even number has 2 as a factor so if the number has itself , 2 and 1 as factors it can not be prime. 2 is an even number that has only itself and 1 as factors so it is the only even number that is a prime.

Answer. Answer: Approach: The sum of two prime numbers is always even which is composite as they are odd numbers except 2.

Two even (and therefore composite) numbers add up to an even number. Two odd numbers (composite or prime) add up to an even number. So, if two composite numbers are to sum to a prime number, one of them must be even and one must be odd.

The sum of two prime numbers is not always even. Because of every prime number is an odd number except 2, However, adding two odd numbers always results in an even number. If you add any prime numbers with 2 it will be odd. The sum of two prime numbers except 2, are always even.

The sum of two primes is always even: This is only true of the odd primes. 2 is also a prime number, however, and 2 plus an odd number is odd. Every positive prime has a corresponding negative prime: This is also false. There are no negative primes.

As a result, no other even number can be a prime, and all other even numbers are multiples of 2. 2 is the only even prime number. The number 3 is also a prime number. This is because it has only two factors: 1 and itself, 3.

The first 25 prime numbers (all the prime numbers less than 100) are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97 (sequence A000040 in the OEIS).

Informally: When you multiply an integer (a “whole” number, positive, negative or zero) times itself, the resulting product is called a square number, or a perfect square or simply “a square.” So, 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, and so on, are all square numbers.

2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30 are even numbers. Odd numbers always end with a digit of 1, 3, 5, 7, or 9. 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31 are odd numbers.

2 is not an odd number.

The number 2 has only two whole number factors, 1 and itself. That’s pretty much it after this: The other numbers that are even up from two are all divisible by that number in some way. This is also known as the “oddest prime” because it’s the only prime number that’s even, so it’s also known as the odd one out.

2

The first five even natural numbers are 2, 4, 6, 8, 10…

Input parameters & values: The number series 2, 4, 6, 8, 10. Therefore, 30 is the sum of first 5 even numbers.

Answer: The number series 2, 4, 6, 8, 10. Therefore, 30 is the sum of the first 5 even numbers.

The number series 1, 3, 5, 7, 9. Therefore, 25 is the sum of first 5 odd numbers.

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

Answer: The sum of the first 20 odd natural numbers is 400.

The number series 1, 3, 5, 7, 9, . . . . , 49. Therefore, 625 is the sum of first 25 odd numbers.

The number series 1, 3, 5, 7, 9, . . . . , 19. Therefore, 100 is the sum of first 10 odd numbers.

The number series 1, 3, 5, 7, 9, . . . . , 99. Therefore, 2500 is the sum of first 50 odd numbers.

So 79 CANNOT be the sum of two prime numbers.

Algorithm to check whether a number can be expressed as a sum of two prime numbers

1. Input the number to be checked.
2. Repeat from i = 2 to (num/2).
3. Check if (i) is a prime number.
4. If i is prime, check if (n – i) is a prime number.

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29 is the smallest positive whole number that cannot be made from the numbers {1, 2, 3, 4}, using each exactly once and using only addition, subtraction, multiplication, and division.

Answer. the divisibility rule of 28 is that it should be divisible by 7 and 4.

Another biblical fact about number 28 is that the Gospel of Matthew has 28 chapters. There are also many other facts about number 28 and its meaning in the Bible. For example, we have to say that the king of Israel, whose name was Jehu, was on the throne 28 years.

Using a calculator, if you typed in 17 divided by 2, you’d get 8.5. You could also express 17/2 as a mixed fraction: 8 1/2.

The quotient (integer division) of 19/2 equals 9; the remainder (“left over”) is 1. 19 is the dividend, and 2 is the divisor.