Question

writing a basic math program to help me understand python math calculation.

if I write

x = 15 + 30 + 45
print(x)

I get

90

if I write

x = 90 / 3
print(x)

I get

30.0

but if I write

def avg3():
    print("This program will calculate the average of 3 scores")
    scores = eval(input("enter 3 scores: "))
    average = scores[0] + scores[1] + scores[2] / 3
    avg = str(average)
    print("The average of the input scores is " + avg + ".")

avg3()

and input

15, 30, 45

what is returned is

The average of the input scores is 60.0.

of course I’m expecting 30. What’s going on here?

Answer 1

You need parentheses in your average, like this:

average = (scores[0] + scores[1] + scores[2]) / 3

Otherwise, you are just dividing scores[2] by 3.