//C++ program to print the single digit sum of digits of a given number
#include 
#include 

int main()
{
	int n,sum=0;
	clrscr();
	cout<<"Enter a number"; cin>>n;
	while(n>0)
	{
		sum+=n%10;
		n/=10;
	}
	if(sum>9)
	{
		n=sum;
		sum=0;
		while(n!=0)
		{
			sum+=n%10;
			n/=10;
		}
	}
	cout<<"\nSum of digits: "<
     Source: geocities.com/cplusplussurvivalkit