public int determineBox () {
        if (this.row < 3) {
            if (this.col < 3) {
                this.box = 1;
                return this.box;
            }
            else if (this.col < 6) {
                this.box = 2;
                return this.box;
            }
            else {
                this.box = 3;
                return this.box;
            }
        }
        else if (this.row < 6) {
            if (this.col < 3) {
                this.box = 4;
                return this.box;
            }
            else if (this.col < 6) {
                this.box = 5;
                return this.box;
            }
            else {
                this.box = 6;
                return this.box;
            }
        }
        else {
            if (this.col < 3) {
                this.box = 7;
                return this.box;
            }
            else if (this.col < 6) {
                this.box = 8;
                return this.box;
            }
            else {
                this.box = 9;
                return this.box;
            }
        }
    }