how to calculate percentage in python

Question

This is my program

print" Welcome to NLC Boys Hr. Sec. School "
a=input("\nEnter the Tamil marks :")
b=input("\nEnter the English marks :")
c=input("\nEnter the Maths marks :")
d=input("\nEnter the Science marks :")
e=input("\nEnter the Social science marks :")
tota=a+b+c+d+e
print"Total is: ", tota
per=float(tota)*(100/500)
print "Percentage is: ",per

Result

Welcome to NLC Boys Hr. Sec. School 

Enter the Tamil marks :78

Enter the English marks :98

Enter the Maths marks :56

Enter the Science marks :65

Enter the Social science marks :78 Total is:  375 Percentage is:  0.0

However, the percentage result is 0. How do I calculate the percentage correctly in Python?

Answer 1

I guess you're learning how to Python. The other answers are right. But I am going to answer your main question: "how to calculate percentage in python"

Although it works the way you did it, it doesn´t look very pythonic. Also, what happens if you need to add a new subject? You'll have to add another variable, use another input, etc. I guess you want the average of all marks, so you will also have to modify the count of the subjects everytime you add a new one! Seems a mess...

I´ll throw a piece of code where the only thing you'll have to do is to add the name of the new subject in a list. If you try to understand this simple piece of code, your Python coding skills will experiment a little bump.

#!/usr/local/bin/python2.7

marks = {} #a dictionary, it's a list of (key : value) pairs (eg. "Maths" : 34)
subjects = ["Tamil","English","Maths","Science","Social"] # this is a list

#here we populate the dictionary with the marks for every subject
for subject in subjects:
   marks[subject] = input("Enter the " + subject + " marks: ")

#and finally the calculation of the total and the average
total = sum(marks.itervalues())
average = float(total) / len(marks)

print ("The total is " + str(total) + " and the average is " + str(average))

Here you can test the code and experiment with it.