Prime number: It is a natural number which can be divided by 1 and itself.
Eg:
1,2,3,5,7,11,13,17,19,…
Prime number is a unique number. It has only two factors. They are 1 and the prime number.
#Java Program
to check the given number is prime or not:
Logic
behind the Program:
- · First, we get a number as input.
- · Next,set a flag setPrime as true.
- · If the input is less than 1,set the
flag setPrime as false.
- · Else, start the process.
- · Check with for loop until the the
square root of the number.
- · For each i value,check the number is
divided by i or not. If it divided by i, then quit the loop.
- · Other wise continue the loop.
- · Finally,check the flag setPrime value.
- · If it is true, then print the given
number is prime number.
- · Otherwise, print the given number is
not a prime number.
public
class PrimeNumber {
public static void main(String args[]) {
int no = 37;
int i;
Boolean setPrime = true;
if(no <= 1)
{
setPrime = false;
}
else
{
for (i=2;i<=Math.sqrt(no);i++)
{
if (no % i == 0)
{
setPrime = false;
break;
}
}
}
if(setPrime)
{
System.out.println("Given
number "+ no +" is a prime number");
}
else
{
System.out.println("Given number
"+ no +" is not a prime number");
}
}
}
When you
execute this program, you get the below output.
Change the
no value as 33 and check the output.
Prime numbers are useful in mathematics and cryptography. It generates the public and private keys in encryption and decryption.
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