public static char assignLetterGrade (int score) {


        char letterGrade;

        if(score == 100)
            letterGrade = 'A';
        else if(score == 90)
            letterGrade = 'B';
        else if(score == 80 || score ==70)
            letterGrade = 'C';
        else if(score == 60 || score == 50)
            letterGrade = 'D';
        else
            letterGrade = 'F';


        return letterGrade;
    }