Therefore, we can say that number 8 is a composite number. So the factors of 8 are 1, 2, 4, as well as 8. The number 8 can be written as 8 × 1, 1 × 8, 2 × 4, and 4 × 2. Therefore, we can say that number 6 is a composite number. So, the factors of number 6 are 1, 2, 3, and 6.
Now, let us take a number, say 6, that can be written as 6 × 1, 1 × 6, 2 × 3, and 3 × 2. Therefore, we can say that 4 is a composite number as it has only 2 factors. It can be written as 4 × 1, 1 × 4, and 2 × 2 So the factors of 4 are 1, 2, and 4. Total number of prime numbers from 1 to 1000 = 168Ĭomposite numbers are numbers that have at least one factor other than the number itself and 1.
In other words, we can say that two is the only even prime number. Some of the properties of prime numbers are:Įvery number that is greater than 1 can be divided by at least one prime number.Įvery even positive integer greater than the number 2 can be expressed as the sum of two primes.Įxcept for number 2, all other prime numbers are odd. Students can practice this method, by writing the positive integers from the numbers 1 to 1000 and circling the prime numbers, and putting a cross mark to all the composite numbers. Eratosthenes took the example of a sieve to filter out the prime numbers from a list of natural numbers and drain out the composite numbers. The prime number was discovered by Eratosthenes (275-194 B.C.). So any prime number should have only two factors and the number should be greater than 1. Then, list all of the factors of each number to identify the prime ones.
This means that number 1 can never be a prime number. To identify prime numbers within a range, there is not a formula, so the best. Similarly, we can say for the numbers 2, 3, 5, 7, 13, 17, … etc can only be written in two forms with a single factor as 1, hence are the prime numbers.Įach prime number is only divisible by the number 1 and itself. So, we can say that 11 is a prime number. There is no other way of writing the number 11. Let us see a few examples of prime numbers and the list of prime numbers from 1 to 1000.įor example, let us take a number for example 11. The prime number is known to be the simplest of a number. The numbers that have factors 1 and number itself are known as prime numbers. Every prime number has exactly 2 factors.
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