Accepts an exam score as input and prints the corresponding letter grade

U05_Ex03_GradingScale.py

# U05_Ex03_GradingScale.py
#
#  Author: Bill Montana
#  Course: Coding for OOP
# Section: A3
#    Date: 30 Oct 2017
#     IDE: Pythonista for iOS
#
# Assignment Info
#   Exercise: 3
#     Source: Python Programming
#    Chapter: 5
#
# Program Description
#   Accepts an exam score as input and prints the corresponding letter grade
#
# Algorithm (pseudocode)
#   Print intro
#	 Get exam score from user
#	 Get index by integer dividing by 10
#	 Print letter grade using index

def main():
	#   Print intro
	print('This program converts a numeric grade (0-100) to a letter grade (A,B,C,D,F)\n')
	
	#	 Get exam score from user
	examGrade = int(input('Please enter the exam grade: '))
	
	#	 Get index by integer dividing by 10
	idx = examGrade // 10
	# letters = ['F'*6, 'D', 'C', 'B', 'A']
	letters = 'F'*6 + 'DCBAA'
	
	#	 Print letter grade using index
	print('An exam grade of {0} corresponds to a letter grade of {1}.'.format(examGrade, letters[idx]))
	
main()

I try to use concepts from the chapter in my solutions. To that end, I select the letter grade from a string based on an index determined from the number grade. Note that my first attempt, in which I used a list for letters, did not work.