def main():
    grade = raw_input("Enter the student's grade: ")
    grades = ["F", "F", "D", "C", "B", "A"]
    final = grades[int(grade)]
    print final
 
main()

def main():
    grade = raw_input("Enter the student's grade: ")
    index = int(grade)/10
    grades = ["F", "F", "F", "F", "F", "F", "D", "C", "B", "A"]
    final = grades[int(index)]
    print final
 
main()

def CalcGrade(grade):
    """Converts a numeric grade between 0 and 100 into a letter between 'A' and 'F' """
    index = int(grade)/10
 
    #Added another "A" to grades list to handle perfect grade of 100
    grades = ["F", "F", "F", "F", "F", "F", "D", "C", "B", "A", "A"]
    final = grades[int(index)]
    return final
 
#grade = raw_input("Enter the student's grade: ")
# Commented out the raw input and used loop to test all values
for x in range(101): #Test for values between 0 and 100
    print x, " Converts to ", CalcGrade(x)

# create a string where the index gives the grade
grade_str = 'F'*60 + 'D'*10 + 'C'*10 + 'B'*10 + 'A'*11
# ask for grade number input
grade = int(raw_input("Enter the student's grade (0 to 100): "))
# index the result
print "Grade letter =", grade_str[grade]

>>> def grades():
	grade = int(raw_input("Enter the student's grade: "))
	if grade >= 90:
		return 'A'
	if grade >= 80:
		return 'B'
	if grade >= 70:
		return 'C'
	if grade >= 60:
		return 'D'
	return 'F'
 
>>> grades()
Enter the student's grade: 55
'F'
>>> grades()
Enter the student's grade: 93
'A'
>>> grades()
Enter the student's grade: 72
'C'