Prime Numbers Up to 100
Any whole number which is greater than 1 and it is divisible only by 1 and the number itself, is known as a prime number. Prime numbers up to 100 are all the prime numbers that come between 1 and 100. The formula of prime numbers helps in representing the general form of a prime number. In mathematics, we have seen that the numbers are classified into different types. In this article, we will discuss one of the types that is prime numbers. Let us discuss in detail its definition, how to find out the prime numbers up to 100 by Eratosthenes' method, and the list of prime numbers up to 100.
1.  Definition of Prime Numbers 
2.  How to find Prime Numbers Up to 100 
3.  List of Prime Numbers Up to 100 
4.  Solved Examples 
5.  Practice Questions 
6.  FAQs on Prime Numbers Up to 100 
Definition of Prime Numbers
The numbers having only two factors that is one and the number itself or we can say that the numbers that are divisible by themselves and by one are known as prime numbers. After reading the definition of prime numbers the question that arises is what are the factors. A factor is a number that exactly divides the given number.
Any given number has one and itself as its factors is defined as a prime number in mathematics. In other words, if a number cannot be divided into equal groups, then it is a prime number. We can divide a number into groups with equal numbers of items only if it can be factorized as a product of two numbers. For example, 5 cannot be divided into groups of equal numbers. This is because 5 can only be factorized as follows:
 5 × 1 = 5
 1 × 5 = 5
There are only two factors of 5 that is one and the number itself, therefore 5 is a prime number.
Number 1 is neither a prime number nor a composite number as it has only one factor that is one itself and prime numbers are those numbers having two factors that is one and the number itself.
Important Notes:
 Prime numbers are positive numbers greater than 1.
 A number can be a prime number if it is a nonzero whole number.
 Prime numbers are natural numbers that have only two factors one and the number itself.
 Prime numbers cannot be divided by any other number except the number 1 and the number itself.
 Integer factorization or prime factorization is the method to find prime numbers.
How to Find Prime Numbers up to 100?
We can find prime numbers in mathematics by using an ancient technique that is the sieve of Eratosthenes. It is an ancient method for finding all the prime numbers up to any given limit. Following are the steps to find all the prime numbers up to 100 by Eratosthenes' method. Leave the number 1 as all prime numbers are greater than one.
 Step 1: First create a list of integers from 2 to 100: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100.
 Step 2: The number 2 is the first number in the list and it is a prime number too; cross out every 2nd number in the list after 2 by adding 2 or skip counting by 2s. For example, 2+2=4, 4+2=6, and so on (these will be all the multiples of 2 in the list): Such as 4,6,8,10,12,14,16 and so on up to 100
 Step 3: 3 is the next number in the list after; cross out every 3rd number in the list after 3 by adding 3 or skip counting by 3s. For example, 3+3=6, 6+3=9, and so on (these will be all the multiples of 3 in the list): Such as 6,9,12,15,18,21,24 and so on up to 100
 Step 4: 5 is the next number in the list after 3; cross out every 5th number in the list after 5 by adding 5 or skip counting by 5s. For example, 5+5=10, 10+5 = 15, and so on (these will be all the multiples of 5 in the list):Such as 10,15,20,25,30 and so on up to 100
 Step 5: 7 is the next number in the list after 5; the next step would be to cross out every 7th number in the list after 7, by adding 7 or skip counting by 7s. For example, 7+7=14, 14+7=21, and so on (these will be all the multiples of 7 in the list) such as 14,21,28,35,42,49,56,63 and so on up to 100
The numbers marked yellow in the below chart are all the prime numbers up to 100.
List of Prime Numbers Up to 100
Following is the list of prime numbers up to 100:
Prime numbers between 1 and 10
2, 3, 5, 7
Prime numbers between 11 and 20
11, 13, 17, 19
Prime numbers between 21 and 30
23, 29
Prime numbers between 31 and 40
31, 37
Prime numbers between 41 and 50
41, 43, 47
Prime numbers between 51 and 100
53, 59, 61, 67, 71, 73, 79, 83, 89, 97
So, there are total 25 prime numbers up to 100.
Some facts on prime numbers:
 2 is the only even prime number and the remaining even numbers are not prime numbers as they can be divided by 2.
 Any prime number greater than 5 and ends with a 5 can be divided by 5 so it cannot be a prime number.
 Prime numbers have exactly two factors therefore 0 and 1 are not prime numbers.
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Solved Examples

Example 1: Which of the given two numbers is a prime number, 13 or 15?
Solution:
Given numbers are 13 and 15.
1, 3, 5, 15 are the factors of 15. So number 15 has more than two factors.
1 and 13 are the only factors of number 13. So number 13 has exactly two factors.
Therefore, number 13 is the prime number as it has only two factors and 15 is not prime number as it has more than two factors. 
Example 2: Why 18 is not a prime number?
Solution:
Given number is 18.
1, 2, 3, 6, 9, and 18 are the factors of 18. So number 18 has more than two factors.
Since number 18 has more than two factors, therefore number 18 is not a prime number.
FAQs on Prime Numbers Up to 100
How to Find Prime Numbers?
We can find prime numbers in mathematics by using an ancient technique that is the sieve of Eratosthenes. It is an ancient method for finding all the prime numbers up to any given limit. Through this technique we select the first number from the list of natural numbers from 2 to 100, and then we cancel all the multiples of that number. With this method, we can easily find out prime numbers.
What is the Difference Between a Prime and a CoPrime Number?
A prime number is a number that has only two factors, that is, 1 and the number itself. For example, 2, 3, 5, 7 are prime numbers. Coprime numbers are the numbers whose highest common factor is 1. For example, 2 and 3 are coprime numbers. Coprime numbers can be prime numbers too or nonprime numbers too.
Is 87 a Prime Number?
A number is called prime if it does not have any factors except 1 and itself. Here, the prime factorization of 87 is 3 × 29. So, it has 3 and 29 also as factors along with 1 and 87. Hence it is a composite number. Thus, 87 is not a prime number.
What are Twin Prime Numbers?
The pair of primes that differ by 2 are known as twin prime numbers.
What is the HCF of Smallest Prime Number and The Smallest Composite Number?
Prime numbers are the numbers that have exactly two factors, that are, 1 and the number itself. The smallest prime number is 2 and the smallest composite number is 4. Therefore, the HCF of smallest composite number and smallest prime number is 2.
How many Prime Numbers are There Between 1 and 100?
There are total 25 prime numbers up to 100. Following is the 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 and 97.