The program checks if a number is prime or not by using a for loop to divide the number by integers from 1 to itself, counting the number of times it is exactly divisible. If the count is 2, it means the number is only divisible by 1 and itself, so it prints that the number is prime. Otherwise, it prints that the number is not prime.

1. PRIMEORN
//write a progaram to check a number is prime or not.
#include<stdio.h>
#include<conio.h>
void main()
{
int i,n,c=0;
clrscr();
printf("enter any number:");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
if(n%i==0)
{
c++;
}
}if(c==2)
{ printf("%d is a prime no.",n); }
else
{ printf("%d is not a prime no.",n); }
getch();
}
//created by: ankit dubey
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