A Program that calculates the sum of the digits entered by the user successively until the sum reduces to a single digit

In this page I have written the program that calculates the sum successively until the sum reduces to a single digit. For this I have used nested loop as while and do while. For example, 12345=>1+2+3+4+5=>15=>1+5=>6. For more information have a look for the source code and the output below:
The output of the program is:

The main source code for the above program is:

	#include<stdio.h>
	#include<conio.h>
	int main()
	{
	int sum=0,n,r;
	printf("enter any number\n");
	scanf("%d",&n);
	do
	{
	sum=0;
	while(n!=0)
	{
	r=n%10;
	sum=sum+r;
	n=n/10;
	}
	n=sum;
	}while(n>9);
	printf("\n the required result is=%d",n);
	getch();
	}

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