find the prime factor of the given number

find the prime factor of the given number */
#include<stdio.h>
#include<conio.h>
main()
{
    int i=2,j=0,k,n,arr[15];
    clrscr();
    printf("enter any integer greater than 1:");
    scanf("%d",&n);
    while(i<=n)
    {
        if(n%i==0)
        {
            do{
            arr[j]=i;
            n=n/i;
            j++;
            }while(n%i==0);
        }
        else
        i++;
    }
    printf("prime factors of the number are\n");
     /*    for(k=j-1;k>=0;k--)
    printf("%d\t",arr[k]);    */
    for(k=0;k<=j-1;k++)
    printf("%d\t",arr[k]);
    getch();
}

convert decimal number into binary

// to convert decimal  number into binary
#include<stdio.h>
#include<conio.h>
main()
{
    int n,a[25],i=0,j;
    clrscr();
    printf("\n Enter any integer : ");
    scanf("%d",&n);
    while(n>0)
    {
        a[i]=n%2;
        n=n/2;
        i++;
    }
    for(j=i-1;j>=0;j--)
      printf(" %d ",a[j]);
       getch();
}

find number of digits in the given integer

/* To find the no. of digits in the given integer */
#include<stdio.h>
#include<conio.h>
main()
{
    int x,i=0,a[10],k;
    long n;
    clrscr();
    printf("\n enter an integer :");
    scanf("%ld",&n);
    while(n>0)
    {
    x=n%10;
    a[i]=x;
    n=n/10;
    if(a[i]==0)
        break;
    else
        i++;
    }
    printf("\n The number of digits in the given number are:%d",i);
    printf("\n And the numbers are:");
    for(k=i-1;k>=0;k--)
        printf("\n%d",a[k]);

    getch();
    }

Calculate HCF of two numbers

main()
{
    int a,b;
    clrscr();
    printf("\n Enter any two nos.:");
    scanf("%d %d",&a,&b);
    printf("\n HCF of the two nos.:%d",gcd(a,b));
    getch();
}

    gcd(int n,int d)
    {
      int r;
      do{
         r=n%d;
         n=d;
         d=r; }while(r!=0);
      return(n);
      }

Reverse any given integer

/* to reverse any given integer */
#include<stdio.h>
#include<conio.h>
main()
{
    int n,m,x,sum=0;
    clrscr();
    printf("\ngive the number:");
    scanf("%d",&n);
    m=n;
    while(n>0)
    {
    x=n%10;
    sum=sum*10+x;
    n=n/10;}
    printf("\ngiven number is =%d",m);
    printf("\nreversed number is =%d",sum);
       getch();
       }

find the sum of digits of any given integer

/* to find the sum of digits of  any given integer */
#include<stdio.h>
#include<conio.h>
main()
{
//declare int variable n for number for which have to find addition
//m is for temp variable to store rest value
//x is for the single digit/reminder from whole number
//sum which is initialized as 0 to store a sum of the number
    int n,m,x,sum=0;
//clears the screen
    clrscr();
//print msg to screen to enter a number
    printf("\ngive the number:");
//read input from user and store it to n
    scanf("%d",&n);
//store entered number to temp variable m
    m=n;
// start while number number is greater then 0
  while(n>0)
    {
//divide the number by 10 and store the reminder in x
    x=n%10;
//add x to sum
    sum=sum+x;
//again divide n by 10 and store it to n
    n=n/10;
//again check n>0 if yes go to top else exit while
}
//print the given/inputed digit
    printf("\ngiven number is =%d",m);
//print the sum of digit
    printf("\nsum of digits of given number is =%d",sum);
//wait for response
       getch();
       }