Prime Number in Java

To find whether a number is prime or not, divide the number by 2. If the output is a whole number, then it is not a prime number; if the result is not a prime number, then divide the same number by the following prime numbers like 3, 5, 7, 11 and so on. If the output is a whole number, then it is not a prime number; if not, then it is a prime number.

There is an inbuilt method in java used to program to find prime numbers. The isPrime(int n) method checks whether the passed parameter to the function is a prime number or not. The passed parameter is a prime number, then the function returns True; if the passed parameter is not a prime number, then it returns False. If the number is less than 1 i.e., if(inputNum<=1), the function returns False.

Program a simple algorithm to find prime numbers between 1 to 100. 

1. Start

2. SET a = 0, n = 0, i = 1, j = 1;

3. REPEAT 4 to 11 until n < 100

4. SET j = 1

5. Set a=0

6. REPEAT 7 to 8 until j <= i

7. If i % j == 0 then a = a + 1

8. j = j + 1

9. if a = 2 then print i

10.  N = n + 1

11.  i = i + 1

12.  END

To print all the prime factors for n numbers, program a simple algorithm:

1. While n is divisible by 2, print 2 and divide n by 2. 

2. Now, n is odd. Start a loop from i = 3 to the square root of n. While i divides n, print i, divide n by i, increment i by 2 and continue.

3. If n is a prime number and if it greater than 2, then n is not 1 from the above step. Print n if it is greater than 2.

Yes, you will get a certificate of completion for Prime Number in Java after completing all the modules and cracking the assessment. The assessment tests your knowledge of the subject and badges your skills.