Is my teacher teaching us well?

#Date: Nov. 20. 2012
#Purpose: To write a modular program to simulate a simple calculator.
#Accept two numbers from the user and give the user the option of adding,
#subtracting, multiplying or dividing them. The program executes till the user
#enters 0 for both numbers. Non numeric input should be ignored and an error
#message to that effect should be displayed.

#The menu for asking the operation to be done and returning the choice
def showMenu():
    #Integer choice

    print("------------------ Menu -----------------------")
    print("1:  Add the numbers")
    print("2:  Subtract the numbers")
    print("3:  Multiply the numbers")
    print("4:  Divide the numbers")
    print("5:  Exit") 
    print("-----------------------------------------------")

    try:
        choice = int(input("Please enter your choice(1-5): "))
        #choice must be a value 1 through 5
        while (choice < 1 or choice > 5):
            print("You MUST enter a valid value")
            choice = int(input("Please enter your choice(1-5): "))
        return choice    
    except ValueError:
        print("Non numeric input ignored. Try again...")
    except:
        print("Input Error!!")
###########################################################################
#This function adds two numbers and returns the sum        
def addNumbers(n1,n2):
    #Real n1, n2

    return n1 +n2
###########################################################################
#This function subtracts the smaller number from the bigger number and returns
#the difference
def subtractNumbers(n1,n2):
    #Real n1, n2

    if ( n1 > n2):
        return n1-n2
    else:
        return n2-n1

###########################################################################
#This function returns the product of the two numbers        
def multiplyNumbers(n1,n2):
    #Real n1, n2

    return n1 * n2
###########################################################################
#This function divides the first number by the second number and returns the quotient        
def divideNumbers(n1,n2):
    #Real n1, n2

    return n1/n2
###########################################################################
def printResults(number1, number2, summation, sumFlag, difference, diffFlag, product, prodFlag, quotient, quoFlag):
    #Boolean sumFlag, diffFlag, prodFlag, quoFlag    
    #Real number1, number2, summation, difference,  product, quotient

    print("-------------------- O U T P U T ---------------------------")
    print("Number One           : %.2f" %number1)
    print("Number Two           : %.2f" %number2)
    if (sumFlag):
        print("Sum                  : %.2f" %summation)
    if (diffFlag):    
        print("Positive Difference  : %.2f" %difference)
    if (prodFlag):
        print("Product              : %.2f" %product)
    if(quoFlag):
        print("Quotient             : %.2f" %quotient)
    
    print("------------------------------------------------------------")
    return
#######################################################################################
#This function accepts a number from the user and returns it. It displays
#an error message in case of non-numeric input. Non-numeric input is
#ignored.
def getNumber():
    #Real number

    while(True):
        try:
            number = float(input("Please enter a number: "))
            return number
        except ValueError:
            print("Non numeric input was provided. Try again...")
        except:
            print("Input error!!")
            
############################################################################## 

#The main function hadles the input, processing and output
def main():
    #Real number1, number2, summation, difference, product, quotient
    #Integer choice
    #Boolean sumFlag, diffFlag, prodFlag, quoFlag
   
    
    #get the two numbers
    number1 = getNumber()
    number2 = getNumber()

    #loop while both numbers are not 0
    while (number1 != 0 and number2 != 0):
        
        sumFlag= diffFlag = quoFlag= prodFlag = False
        summation=difference=product=quotient = 0
        
        #show a menu to the user to choose the operation
        choice = showMenu()
        while (choice != 5):
            if (choice ==1):
                summation = addNumbers(number1, number2)
                sumFlag = True
            elif (choice==2):
                difference = subtractNumbers(number1, number2)
                diffFlag = True
            elif(choice == 3):
                product = multiplyNumbers(number1, number2)
                prodFlag = True
            else:
                quotient= divideNumbers(number1, number2)
                quoFlag = True

            choice = showMenu()
            

        #print the results
        printResults(number1, number2, summation, sumFlag, difference, diffFlag, product, prodFlag, quotient, quoFlag)
        
        #get the next pair of numbers
        number1 = getNumber()
        number2 = getNumber()

    return
#############end of main#########################################################
main()