Write a program that prompts the nuser to enter the first 9 digits of an ISBN and disply the 10-digit ISBN (including leading zeros)

Here is what I didi but it's not running help please

the formula is (1 * d1 + 2 * d2 + 3 * d3 + 4 * d4 + 5 * d5 + 6 * d6 + 7 * d7 + 8 * d8 + 9 * d9) % 11;

#include

using namespace std;

int main() { string val, isbn; int check; double val; cout<< "Enter the first 9 digits of an ISBN "; cin.get >> val; if (val.size() == 9); { check = ((val[0] - 48) * 1 + (val[1] - 48) * 2 + (val[2] - 48) * 3 + (val[3] - 48) * 4 + (val[4] - 48) * 5 + (val[5] - 48) * 6 + (val[6] - 48) * 7 + (val[7] - 48) * 8 + (val[8] - 48) * 9) % 11; if (check < 10) isbn = val + char(check + 48); else isbn = val + "X"; cout << "The ISBN 10 number is " << isbn;

} else cout << "ivalid input"; cout << endl; system("pause") return 0;

}