The prime number program in C is one of the most important programs in c.
What is a prime number?
Any number which is divisible only by one and itself. two (2) is the smallest even prime number. for example prime numbers are: 2, 3, 5, 7, 11, 13, 17,…..
A number is greater than one can be factorized into prime numbers, for example, 540 = 22*33*51.

Algorithm for Prime number program in C

  1. Take the input number. no
  2. Set c=2
  3. Write loop for ( c = 2 ; c <= n – 1 ; c++ )
    if n%c == 0
    Print No is not a prime number
    break;
  4. If c == n
    Print No is a prime number

C Program to Check Whether a Number is Prime or not

#include<stdio.h>

main()
{
int n, c = 2;

printf("Enter a number to check if it is prime\n");
scanf("%d",&n);

for ( c = 2 ; c <= n - 1 ; c++ )
{
if ( n%c == 0 )
{
printf("%d isn't prime.\n", n);
break;
}
}
if ( c == n )
printf("%d is prime.\n", n);

return 0;
}

Output :

Prime number program in C

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