C Programming Questions with their programs.

 1. Write C program to display the series: 1,2,3,6,11,20,37 .... up to 10^th terms

#include <stdio.h>

            #include<conio.h> 

void main() {

int i, first = 1, second = 2, next;

printf("The first 10 terms of the series are: \n");

for (i = 1; i <= 10; i++) {

printf("%d, ", first);

next = first + second;

first = second;

second = next;

}

printf("\n");

getch( );

}

2. WAP to check whether a number is Prime or Composite.

#include <stdio.h>

          #include<conio.h> 

void main() {

int n, i, flag = 0;

printf("Enter a positive integer: ");

scanf("%d", &n);

for (i = 2; i <= n/2; i++) {

if (n%i == 0) {

flag = 1;

break;

}

}

if (flag == 1) {

printf("%d is a composite number\n", n);

} else {

printf("%d is a prime number\n", n);

}

getch( );

}

 

 

3. Write a program to find the factorial of a given number:

#include <stdio.h>

            #include<conio.h> 

void main() {

int n, i, fact= 1;

printf("Enter an integer: ");

scanf("%d", &n);

for (i = 1; i <= n; i++)

{

fact =fact*i ;

}

printf("Factorial of %d = %d", n, factorial);

getch( );

}

4. Write a program to find the sum of natural numbers up to n:

#include <stdio.h>

            #include<conio.h> 

void main() {

    int n, i, sum = 0;

    printf("Enter an integer: ");

    scanf("%d", &n);

        for (i = 1; i <= n; i++)

    {

        sum =sum+ i;

    }

    printf("Sum of natural numbers up to %d = %d", n, sum);

   getch( );

}

#include <stdio.h>

     #include<conio.h>

    void main() {

    int n, is_prime = 1;

    printf("Enter a number: ");

    scanf("%d", &n);

    for (int i = 2; i < n; i++) {

        if (n % i == 0) {

            is_prime = 0;

            break;

        }

    }

    

    if (n == 1) {

        is_prime = 0;

    }

    if (is_prime) {

        printf("%d is a prime number.\n", n);

    } else {

        printf("%d is not a prime number.\n", n);

    }

getch( );

}