# Prime Numbers from 1 to 100

Numbers are very useful to human beings and are used in day-to-day life. Mathematics has different types of numbers. Prime numbers are one of the important ones.

## Definition of Prime Numbers

The prime number is defined as a positive integer that is divisible by only 1 and itself i.e., there is no number other than 1 and itself that divides a prime number.

## Properties of Prime Numbers

Various properties that are possessed by prime numbers are:

• Prime numbers are positive numbers greater than 1.
• For a number to be a prime number, it must be a non-zero whole number.
• Prime numbers are numbers that cannot be divided by any number except themselves and one.
• Prime numbers have only two factors.
• The way of finding prime numbers is called integer factorization or prime factorization.

## List of prime numbers up to 100

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.

## Facts that are related to Prime Number

2 is the only even prime number and the remaining even numbers can be divided by 2. So, it can't be a prime number.

There is no prime number greater than 5 ends with a 5. Because any number greater than 5 that ends with 5 can be divided by 5, it can't be a prime number.

Zero and one are not prime numbers.

The numbers 0, and 1, are neither prime numbers nor composite numbers.

## Largest Prime Number

Greek mathematician Euclid (one of the most famous mathematicians of the classical era), recorded proof that there is no largest prime number among the set of primes. However many scientists and mathematicians are still searching to find it as part of the Great Internet Mersenne Prime Search.

The largest known prime number (as of November 2020) is 282,589,933 - 1, a number that has 24,862,048 digits when written in base 10. Before then the largest known prime number was 277,232,917 - 1, having 23,249,425 digits.

## The technique to find prime numbers from 1 to 100 are

The steps to write prime numbers from 1 to 100:

• The number 1 is to be kept as it is because all primes are greater than 1.
• The number 2 is to be highlighted and keep the numbers as it is which are multiples of 2. (e.g., 2, 4, 6, 8, 10….)
• The number 3 is a prime number, so highlight the number 3, and keep the numbers as it is which are multiples of 3. (e.g., 6, 9, 12, 15….)
• The next number left is 5, so highlight the number 5 and keep the numbers as it is which are multiples of 5(such as 10, 15, 20, 25, 30…)
• In the end, the number left in the first row is number 7, now highlight the number 7 and keep all the numbers that are multiples of 7( such as 14, 21, 28, 35…)
• Finally, all the leftover highlighted numbers in the table are prime numbers.

## Use of Prime Numbers in the real world

• Cyber security is one of the fields where prime numbers are used to a greater extent. The use of prime numbers makes information shared over the internet safer.
• In order to encrypt (make secure) things like credit card details, medical records, and even some messaging services like WhatsApp, software engineers make algorithms using prime numbers.
• By multiplying two very large prime numbers together (some companies use prime numbers that are hundreds of digits long!), we create an even larger number whose original factors (the two very large prime numbers) are only known to us. We then use this even larger number to encrypt our information.
• If anyone else wants to discover what information we are sending, they have to find out what our original factors were. With prime numbers as long as the ones we have used, it could take them years or even decades of constant trial and error before they find even one. This kind of public-key cryptography ensures our information is kept safe.

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