# C++ FAQ - How to add the individual digits of a given number?

To solve this problem, you need to do mod (modulus %) and  division (/) operations in a for loop until you reach single digit.

Look at the sample code and output! It is easy to understand.

## Source Code

#include <iostream>

#include <tchar.h>

// Adding the individual digits of a given number

int _tmain(int argc, _TCHAR* argv[])

{

while(1)

{

int input = 0;

std::cout << "\nEnter a number (-1 to exit): ";

std::cin >> input;

if( input < 0)

break;

int sum = 0;

int j = 0;

for(; input >= 10; j++)

{

sum += input % 10;

input = (input / 10);

}

sum += input;

j++;

std::cout << "Number of digits: " << j;

std::cout << "\tSum of digits: " << sum;

std::cout << "\n\n";

}

return 0;

}

## Output

Enter a number (-1 to exit): 100

Number of digits: 3     Sum of digits: 1

Enter a number (-1 to exit): 123

Number of digits: 3     Sum of digits: 6

Enter a number (-1 to exit): 555

Number of digits: 3     Sum of digits: 15

Enter a number (-1 to exit): 6666

Number of digits: 4     Sum of digits: 24

Enter a number (-1 to exit): 88888

Number of digits: 5     Sum of digits: 40

Enter a number (-1 to exit): -1