Factorial of number

Program:

#include<stdio.h> 
int main() 
{ 
int num,i,fact=1; 
  printf("Enter Number: \n"); 
  scanf("%d",&num); 
  if(num<0)
{
     printf("Factorial of a negative number not defined");
  } 
  else
  {
for(i=1;i<=num;i++) 
  { 
  fact=fact*i; 
  }
  printf("Factorial of %d : %d ",num,fact);
}
return 0;
}

Output:

Palindrome number

Program:

#include<stdio.h>
int main()
{
int n,rev=0,rem,temp;
printf("Enter number: ");
scanf("%d",&n);
temp=n;
while(n>0)
{
rem=n%10; //separate the digit
rev=(rev*10)+rem; //reverse of number
n=n/10;
}
if(temp==rev)
{
printf("Palindrome number");
}
else
{
printf("Not a Palindrome number");
}
return 0;
}

Output:

Fibonacci series

Program:

#include<stdio.h> 
int main() 
{ 
int n1=0,n2=1,n3,i,num; 
  printf("Enter No. of elements: \n"); 
  scanf("%d",&num); 
  printf("%d %d",n1,n2); 
  for(i=2;i<num;i++) 
  { 
  n3=n1+n2; 
  printf(" %d ",n3); 
  n1=n2; 
  n2=n3; 
  }
return 0;
}

Output:

Prime number

Program:

#include<stdio.h>
int main()
{
int i,n,flag=0;
printf("Enter number: ");
scanf("%d",&n);
for(i=2;i<n;i++)
{
if(n%i==0)
{
flag=1;
break;
}
}
if (n == 1)
 {
      printf("1 is neither a prime nor a composite number.");
  }
 else
 {
      if(flag==0)
{
printf("%d is a prime number",n);
}
else
{
printf("%d is not a prime number",n);
}
}
return 0;
}

Output:

Armstrong number

Program:

#include<stdio.h>
int main()
{
int n,sum=0,rem,temp;
printf("Enter number: ");
scanf("%d",&n);
temp=n;
while(n>0)
{
rem=n%10; /*separate the digit*/
sum=sum+(rem*rem*rem); /*cube of digit and add to sum*/
n=n/10; /*new n after separation of digit*/
}
if(sum==temp)
{
printf("Armstrong number");
}
else
{
printf("Not a Armstrong number");
}
return 0;

}

Output:

Reverse number

Program:

#include<stdio.h>
int main()
{
int n,rev=0,rem;
printf("Enter number: ");
scanf("%d",&n);
while(n>0)
{
rem=n%10;
rev=rev*10+rem;
n=n/10;
}
printf("Reverse of number= %d",rev);
return 0;
}

Output:

Sum of digit

Program:

#include<stdio.h>
int main()
{
int n,sum=0;
printf("Enter number: ");
scanf("%d",&n);
while(n>0)
{
sum=sum+(n%10);
n=n/10;
}
printf("Sum of digit= %d",sum);
return 0;

}

Output:

Sum of first N

Program:

#include<stdio.h>
int main()
{
int n,sum=0,i=1;
printf("Enter number: ");
scanf("%d",&n);
while(i<=n)
{
sum=sum+i;
i++;
}
printf("Sum of first %d number: %d",n,sum);
return 0;

}

Output: