#include<stdio.h>
int main(){
    int k,r;
    long int i=0l,j=1,f;

    //Taking maximum numbers form user
    printf("Enter the number range:");
    scanf("%d",&r);

    printf("FIBONACCI SERIES: ");
    printf("%ld %ld",i,j); //printing firts two values.

    for(k=2;k<r;k++){
         f=i+j;
         i=j;
         j=f;
         printf(" %ld",j);
    }
  
    return 0;
}
Sample output:
Enter the number range: 15
FIBONACCI SERIES: 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377

#include<stdio.h>
int main(){

    int i,range;
    long int arr[40];

    printf("Enter the number range: ");
    scanf("%d",&range);

    arr[0]=0;
    arr[1]=1;

    for(i=2;i<range;i++){
         arr[i] = arr[i-1] + arr[i-2];
    }

    printf("Fibonacci series is: ");
    for(i=0;i<range;i++)
         printf("%ld ",arr[i]);
  
    return 0;
}
Sample output:
Enter the number range: 20
Fibonacci series is: 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181

#include<stdio.h>
int main(){
    int k=2,r;
    long int i=0l,j=1,f;

    printf("Enter the number range:");
    scanf("%d",&r);

    printf("Fibonacci series is: %ld %ld",i,j);

    while(k<r){
         f=i+j;
         i=j;
         j=f;
         printf(" %ld",j);
          k++;
    }
  
    return 0;
}
Sample output:
Enter the number range: 10
Fibonacci series is: 0 1 1 2 3 5 8 13 21 34

#include<stdio.h>
int main(){
    int k,r;
    long int i=0,j=1,f;
    long int sum = 1;

    printf("Enter the number range: ");
    scanf("%d",&r);

    for(k=2;k<r;k++){
         f=i+j;
         i=j;
         j=f;
         sum = sum + j;
    }

    printf("Sum of Fibonacci series is: %ld",sum);
  
    return 0;
}
Sample output:
Enter the number range: 4
Sum of Fibonacci series is: 4

#include<stdio.h>
int main(){
  int i=1,f=1,num;

  printf("Enter a number: ");
  scanf("%d",&num);

  while(i<=num){
      f=f*i;
      i++;
  }

  printf("Factorial of %d is: %d",num,f);
  return 0;
}
Sample output:
Enter a number: 5
Factorial of 5 is: 120