Just use long arithmetics and calculate 36*pow(55,k-1);

How did u get the formula

What are the libraries and functions u use for long arithmetic in c++.

There are no such libraries! You must write long arithmetics by yourself ;)

Thank finaly something extra ordinary good.
Thanks allot. I was searching for this for so long time. Thanks, thanks, thanks...

This program explain how get 36 and 55.


#include <iostream>
using namespace std;

__int64 s( __int64 x ){
    __int64 ans = 0;
    while( x ){
        ans += x % 10;
        x /= 10;
    }
    return ans;
}

int main(){
    __int64 kol = 0;
    for( __int64 i = 0; i <= 9; ++i ){
    for( __int64 j = 0; j <= 9; ++j ){
            if( s(i+j) == s(i)+s(j) && i+j<=9 ){
                cout << "    " << i << " " << j << "        s=" << s(i+j) << endl;
                ++kol;
            }
        }
        cout << "-------------------------" << endl;
    }
    cout
    << "kol = "
    << kol << endl;

    kol = 0;
    for( __int64 i = 1; i <= 9; ++i ){// последний разряд без нулей т.к. число must be без ведущих нулей
    for( __int64 j = 1; j <= 9; ++j ){
            if( s(i+j) == s(i)+s(j) && i+j<=9 ){
                cout << "    " << i << " " << j << "        s=" << s(i+j) << endl;
                ++kol;
            }
        }
        cout << "-------------------------" << endl;
    }
    cout
        << "kol = "
        << kol << endl;
    return 0;
}

Edited by author 23.11.2011 03:11

Edited by author 23.11.2011 03:12

Edited by author 23.11.2011 03:12

Thanks for your code.