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I am new to Python and a student, my college has chosen the worst book on earth for our course. I cannot find examples of any concepts, so I apologize in advance as I know these concepts are very basic. I hope you can help me.

I need to know how to use the round feature in a string. I find examples but they do not show the string, just simple numbers.

Here is what we are supposed to get as an output: Enter the gross income: 12345.67 Enter the number of dependents: 1

The income tax is $-130.87 <---- this is what we are supposed to figure out

Here is the coding we are given to alter:

TAX_RATE = 0.20
STANDARD_DEDUCTION = 10000.0
DEPENDENT_DEDUCTION = 3000.0

# Request the inputs
grossIncome = float(input("Enter the gross income: "))
numDependents = int(input("Enter the number of dependents: "))   

# Compute the income tax
taxableIncome = grossIncome - STANDARD_DEDUCTION - \
                DEPENDENT_DEDUCTION * numDependents
incomeTax = taxableIncome * TAX_RATE 

# Display the income tax

print("The income tax is $" + str(incomeTax))

As I do not have an NUMBER to plug into the formula - I have to figure out how to use "incomeTax" - I have no idea how to do this. THe book doesnt explain it. Help?

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1
  • incomeTax holds a (float) number. What you want is to format() it as string. Look up format() in the Python docs. Commented Jan 27, 2019 at 2:27

3 Answers 3

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You can use format strings:

print("The income tax is ${:.2f}".format(incomeTax))

If you are using Python 3.6+, you can also use f-strings:

print(f"The income tax is ${incomeTax:.2f}")
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4 Comments

Thank you - I am just starting out I have no clue what an F string is and I doubt this book will explain.... :(
@queenv PEP 498 describes the implementation, and Python 3's f-Strings: An Improved String Formatting Syntax (Guide) is a more approachable guide.
thank you I will add it to the list of alternate books :)
Short reminder that the dollar sign is part of the string and has nothing to do with the formatting. {incomeTax:.2f} is sufficient.
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You can round just before making it a string:

print("The income tax is $" + str(round(incomeTax,2)))

Output:

Enter the gross income: 12345.67
Enter the number of dependents: 1
The income tax is $-130.87
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4 Comments

This has the possibility of only showing one decimal place if incomeTax rounds to a tenth.
You rock!!!! That worked. It was also simple, imagine if I had been given an example to use! I do have a question for you: I notice that I am having a lot of trouble finding examples for concepts. I am googling with no results - am I using incorrect search terms? How can I get the examples I am searching for without having to post in here constantly?
@queenv Happy to help, don't forget to accept after timer is up, i actually think that you didn't understand the point, you were planning to round a string, but actually you can round it before it becomes a string, so searching "round a decimal python" would be it.
@queenv Lol, just saw it too.
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Im a student as well, with the same dumb book and HW.

I tried the above

str(round(incomeTax,2))

and it didn’t work. Maybe I typed something wrong. After playing around I found this to work 

 # Display the income tax

incomeTax = round(incomeTax,2)

print(“The income tax is $” + str(incomeTax))

I hope this helps some other poor soul searching the web for an answer!

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1 Comment

Kindly format your question according to the rules. Please use control+K to write your code.

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