Posted In: IGCSE-H

Definition Of Prime Number:

The numbers either whole or natural which can only be divisible by two whole numbers 1 and number itself.

For a number to be a prime number it should have only two positive divisors 1 and the number itself.

The number 1 is not a prime number as it has only one divisor. All the whole numbers greater than 1 and that can only be divided by 1 and themselves are called prime numbers.

Explaination Of Prime Number:

The prime numbers from 3 and onwards are all odd numbers 2 is the only even number in the prime number list. This is because every even number is divided by at least three whole numbers 1, 2 and number itself. There are 168 prime numbers between 1 to 1000. Here is a prime number chart.


Natural numbers greater than 1 which are not prime numbers are called composite numbers.

0 and 1 are not prime numbers as 0 is not divisible by 1 and the number 1 has only one divisor that is the 1 itself.

1 is not divided by two distinct positive whole / natural numbers, but other numbers like 2 which are prime are divided by two positive distinct whole/ natural numbers.

Every number is divisible by 1 also every number is divisible by itself, then question arises that what is the difference between composite numbers and prime numbers? Here is the answer the prime number is the only that has only two factors 1 and itself while other numbers do have other factors as well. After number 5 that is a prime number no prime number ends with 5, none of the prime numbers ends with 0 also other than 2 no prime number ends with 2 this is because no prime number other than 2 is even.

Example Of Prime And Composite Numbers:

2, 3, 5, 7, 11, 13, 17, 19.... Are prime numbers.
While others 4, 5, 6, 8 ... Are composite numbers.


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