Problems with my random number generator, numbers far out of range

I'm trying to make a Sudoku puzzle generator for a school project, and I have most of the coding and logic worked out for the program, it's just that the random number generator I'm using to assign values to the Sudoku grid are generating numbers far out of the appropriate range, and I can't quite figure out why it's not functioning appropriately. Here's the code for the number generator:

int Sudoku::RNG(int range, int start){
    int randNum;
    randNum = (rand()%range+start);
    return randNum;
}

I've also seeded with

srand(time(NULL)); 

at the very start of my main method.

And here's the code for the method which populates the Sudoku grid with numbers from the RNG() function:

void Sudoku::gridPopulate(int grid [9][9]){
    Solution s;
    int num;
    bool safe;
    for(int i=0;i<9;i++){
        for(int j=0;j<9;j++){
            do{
                safe = false;
                num= RNG(9,1);
                if(s.rowCheck(grid, i, num)&& s.colCheck(grid, j, num) && s.gridCheck(grid, i, j, num)){
                    grid[i][j] = num;
                    cout << "Number entered into grid" << endl;
                    safe = true;
                }
            }while(safe);
        }
    }

Main Method:

int main()
{
    //Program Start
    srand(time(NULL));
    int difficulty;
    int choice;
    int grid[9][9];

    cout << "Welcome to my Sudoku puzzle generator! \nTest your mental muscles and see if you can solve the puzzle!" << endl;

    //Puzzle Generator
    Sudoku game;
    game.gridPopulate(grid);
    cout << "board populated"<< endl;
    cout << "Successful board made" << endl;
    game.displayBoard(grid);
}

Example of erroneous Sudoku board below (formatting is off because of the huge numbers, just ignore the dashes and vertical lines):

1  5013192 4981028 9 |20064 8 5 |1 2 3 |
2  8 5 4 |1995768265 0 2114351727 |28 7670880 7670908 |
3  1 7274056 7 |3 0 7670880 |4 6 7670880 |
   -----------------4  6 7 2 |4199040 1 8 |7670912 -1196314433 4 |
5  1953657218 1 0 |5 4 32 |7 3 7274140 |
6  5 8 1953722109 |2 9 7670916 |7274116 4199040 4358512 |
   -----------------7  0 1953722297 1 |9 1953787893 3 |7274204 4 8 |
8  1953722109 1953722083 8 |4199040 4199040 0 |9 7274160 2 |
9  3 1953746112 1198757840 |6 7274216 4 |4358512 7274368 4358606 |
   -----------------

   1 2 3 4 5 6 7 8 9

The number's it's giving me are sometimes very large, sometimes not. It's kinda baffling me at the moment, any help or advice would be greatly appreciated!