Question:Sum of digits in c using recursion 

#include<stdio.h>

int getSum(int);
int main(){
  int num,sum;
  printf("Enter a number: ");
  scanf("%d",&num);

  sum = getSum(num);

  printf("Sum of digits of number:  %d",sum);
  return 0;
}

int getSum(int num){

    static int sum =0,r;

    if(num!=0){
      r=num%10;
      sum=sum+r;
      getSum(num/10);
    }

    return sum;
}
Sample output:
Enter a number: 45
Sum of digits of number:  9

Question:How to calculate power of a number in c 

#include<stdio.h>
int main(){
  int pow,num,i=1;
  long int sum=1;
  printf("\nEnter a number: ");
  scanf("%d",&num);
  printf("\nEnter power: ");
  scanf("%d",&pow);
  while(i<=pow){
            sum=sum*num;
            i++;
  }
  printf("\n%d to the power %d is: %ld",num,pow,sum);
  return 0;
}

Question:How to add two numbers without using the plus operator in c 

#include<stdio.h>

int main(){
   
    int a,b;
    int sum;

    printf("Enter any two integers: ");
    scanf("%d%d",&a,&b);

    //sum = a - (-b);
    sum = a - ~b -1;

    printf("Sum of two integers: %d",sum);

    return 0;
}
Sample output:
Enter any two integers: 5 10
Sum of two integers: 15

Question:Write a c program or code to subtract two numbers without using subtraction operator 

#include<stdio.h>

int main(){
   
    int a,b;
    int sum;

    printf("Enter any two integers: ");
    scanf("%d%d",&a,&b);

    sum = a + ~b + 1;

    printf("Difference of two integers: %d",sum);

    return 0;
}
Sample Output:
Enter any two integers: 5 4
Difference of two integers: 1

Question:Write a c program to find largest among three numbers using binary minus operator 

#include<stdio.h>
int main(){
    int a,b,c;
    printf("\nEnter 3 numbers: ");
    scanf("%d %d %d",&a,&b,&c);
    if(a-b>0 && a-c>0)
         printf("\nGreatest is a :%d",a);
    else
         if(b-c>0)
             printf("\nGreatest is b :%d",b);
         else
             printf("\nGreatest is c :%d",c);
    return 0;
}

Question:Write a c program to find largest among three numbers using conditional operator 

#include<stdio.h>
int main(){
  int a,b,c,big;
  printf("\nEnter 3 numbers:");
  scanf("%d %d %d",&a,&b,&c);

  big=(a>b&&a>c?a:b>c?b:c);
  printf("\nThe biggest number is: %d",big);

  return 0;
}

Question:C program for generic root 

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

long int num,sum,r;
printf("\nEnter a number:-");
scanf("%ld",&num);

while(num>10){
sum=0;
while(num){
r=num%10;
num=num/10;
sum+=r;
}
if(sum>10)
num=sum;
else
break;
}
printf("\nSum of the digits in single digit is: %ld",sum);
return 0;
}

Question:C code for calculation of generic root in one line 

#include <stdio.h>
int main(){         
int num,x;
printf("Enter any number: ");
scanf("%d",&num);
printf("Generic root: %d",(x=num%9)?x:9);
return 0;
}
Sample output:
Enter any number: 731
Generic root: 2

Question:Prime factor of a number in c 

#include<stdio.h>
int main(){
  int num,i=1,j,k;
  printf("\nEnter a number:");
  scanf("%d",&num);
  while(i<=num){
      k=0;
      if(num%i==0){
         j=1;
          while(j<=i){
            if(i%j==0)
                 k++;
             j++;
          }
          if(k==2)
             printf("\n%d is a prime factor",i);
      }
      i++;
   }
   return 0;
}

Question:Write a c program to find out NCR factor of given number 

#include<stdio.h>
int main(){
  int n,r,ncr;
  printf("Enter any two numbers->");
  scanf("%d %d",&n,&r);
  ncr=fact(n)/(fact(r)*fact(n-r));
  printf("The NCR factor of %d and %d is %d",n,r,ncr);
  return 0;
}
 int fact(int n){
  int i=1;
  while(n!=0){
      i=i*n;
      n--;
  }
  return i;
 }