# Why Prime Numbers Matter?

Are prime numbers natural numbers? Natural numbers are a set of all the whole numbers excluding 0 and are used for counting objects. On the other hand, prime numbers are natural numbers greater than 1.

Prime numbers only have two factors, 1 and the number itself. This means these numbers cannot be divided by any number other than 1 and the number itself without leaving a remainder, e.g 2, 3, 5, 7, 11, etc. Numbers that have more than 2 factors are known as composite numbers.

**Composite & Prime Numbers**

Have you ever wondered why the day is divided into exactly 24 hours and the circle into 360 degrees? The number 24 has an interesting property. It can be divided into perfectly equal parts in relatively many ways. For example, 24 ÷ 2 = 12, 24 ÷ 3 = 8, 24 ÷ 4 = 6 (fill in the rest of the options yourself!). This means that the day can be divided into two equal parts, 12 hours of day and night. In a factory that works non-stop eight-hour shifts, the day is divided into exactly three shifts.

This is also the reason why the circle is divided into 360°. If the circle is divided into 2, 3, 4, 10, 12, or 30 equal parts, each part contains an integer number of degrees. There are other ways to split the circle that you haven't mentioned. In ancient times, it was necessary to divide a circle very precisely into equally sized sectors for various artistic, astronomical, and technical purposes. Dividing the circle into equal halves was of great practical value, as the only instruments available were a compass and a protractor.

An integer that can be written as the product of two small numbers is called a composite number. An integer that can be written as the product of two small numbers, for example 24 = 3 × 8. For example, the equations 24 = 4 × 6 and 33 = 3 × 11 are, showing that 24 and 33 are composite numbers. Numbers that cannot be resolved in this way are called prime numbers, which are whole numbers that cannot be written as the product of two smaller numbers, such as 7 or 23. The numbers 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 are all prime numbers. In fact, these are the first 10 primes (you can check for yourself if you want!).

**Fun Facts About Prime Numbers**

The largest prime number ever found has 24,862,048 digits.

The largest known prime number today is 282,589,933 – 1. It was discovered on December 7, 2018 by a supercomputer, volunteered by Patrick Laroche. The number is M82589933. To get this value, the computer added 82,589,933 twos and then subtracted 1.

Prime numbers are also called non-composite numbers.

A composite number is a number that has many possible factors. According to this principle, all even numbers except 2 are composite numbers.

The first step in identifying prime numbers is to divide the number by 2.

If you want to know if a number is prime, the first and easiest step is to divide the number by 2. If the quotient of a number divided by 2 is an integer, it is not prime.

Prime numbers that are two spaces apart are called twin primes.

One of the first few twin prime pairs are: (3, 5), (5, 7), (11, 13), (17, 19), (29, 31), (41, 43), (59, 61), (71, 73), (101, 103), (107, 109), (137, 139).

No prime greater than 5 ends in 5.

Some people find numbers difficult to understand, but one of the most interesting facts about prime numbers is their inherent patterns. Any number greater than 5 that ends in 5 is not prime. For example, 15 is the product of (5 x 3) and (15 x 1). 25 is the product of (25 x 1) and (5 x 5). According to this principle, numbers ending in 5 are never prime.

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