Division

[Mallard]

Hi,
I have recently started to look at Python. I found a tutorial pdf document written by Brian Heinold called A Practical Introduction to
Python Programming.
It is interesting and I am enjoying reading it. At the end of the first section there are 9 exercises to have a go at, I have figured out 8 of them but can not get one of them to come up with the answer suggested. Below is the question,
Write a program that computes and prints the result of
512 − 282
47 · 48 + 5
. It is roughly .1017.

[Gribouillis]

Hello, and good luck with your Python programming.

Hint for the exercise: you can use parentheses in Python numeric expressions, for example

>>> (612 - 182) / 7
61.42857142857143
>>> 

[Mallard]

Thanks for the reply.
I tried this way but still didn't get the right answer.

num1=512-282
num2=47.48+5
print(num1/num2)

[deanhystad]

What result do you get? I get 4.382621951219512, which is correct.

Maybe you made a mistake entering the equation. I think you meant to enter:

num1=512-282
num2=47-48+5
print(num1/num2)

When I run that I get 57.5
Or use parenthesis in place of the assignment.
num1=512-282 becomes (512-282)
num2=47-48+5 becomes (47-48+5)
num1 / num2 becomes (512-282) / (47-48+5)

[Pedroski55]

What Gribouillis said: Use brackets, then Python will complete what is in the brackets first, before division.

As I see it you have 4 numbers at the start.

num1 = 512
num2  = 282
num3 = 47.48
num4 = 5

result = (num1 - num2) / (num3 + num4)
print(result)

I got what deanhystad got, so I can't be too far wrong!

Output:
4.382621951219512

Using a Python module called random you can generate random integers. So make 4 random numbers and repeat the above until it is clear to you.!

from random import randint

# randint(start, stop) is inclusive, it can return the first number or the last number
num1 = randint(0, 999)
num2  = randint(0, 999)
num3 = randint(0, 999)
num4 = randint(0, 999)

# have a look at your numbers
print(num1, num2, num3, num4)
result = (num1 - num2) / (num3 + num4)
print(result)

To help you on your Python way there are many, many websites with info on all aspects. I like https://realpython.com, they have stuff for raw beginners and much more complex stuff, but there really is so much info on Python out there, identify your problem, then search, for example: Python module random

[bowlofred]

Some folks seem to be interpreting the dot in the denominator as a decimal point instead of a dot operator. That signifies multiplication in this context. In python, you'll have to use an asterisk for this type of multiplication.

>>> (512-282)/ (47*48+5)
0.1017249004865104

[Mallard]

Thanks to all who took the time to read and reply.
It is, as bowlofred replied, the dot in the denominator should be a multiplication sign to give the answer that the tutorial suggest.
This is a misprint in the pdf document that I am following.
I'm now looking at Chapter 2, For Loops so I could well be back again

[Gribouillis]

This is a misprint in the pdf document that I am following.

It's not a misprint. Mathematicians often use the dot to denote multiplication. It's one of the many differences between the mathematical notations and the syntax of programming languages.

[Will_Smith]

If you write it without parentheses, Python will calculate it incorrectly.

result = (512 - 282) / (47 * 48 + 5)
print(result)

Output:
0.10176.

Conclusion;
If you were missing parentheses, Python was likely evaluating only part of the denominator, which leads to the wrong result.

[Mallard]

This is a misprint in the pdf document that I am following.

It's not a misprint. Mathematicians often use the dot to denote multiplication. It's one of the many differences between the mathematical notations and the syntax of programming languages.

Thanks for the clarification.