# [Tutor] Rounding Error

Michael Lewis mjolewis at gmail.com
Sat Jan 28 06:55:43 CET 2012

```I am trying to round a float to two decimals, but I am getting the
following error:

Traceback (most recent call last):
File "<pyshell#23>", line 1, in <module>
PaintingProject()
File "C:/Python27/Homework/Labs/Lab 03_5.py", line 42, in PaintingProject
print 'That will cost you \$%f.' %(round(5.6523),2)
TypeError: not all arguments converted during string formatting

Basically, I am writing a program to ask a user how many square feet they
need to paint. I then calculate how many cans of paint they need and will
also show the total purchase price. I've tried this two ways, and the first
way I am semi-successful meaning that my output is rounding but it displays
a number of zero's after the number rounds. The second way, I am getting
the error mentioned above. What am I doing wrong? How can I do this better?
(note, for the sake of brevity, I only show the code in question and not
the whole program).

total = PRICE_PER_CAN * cans + (PRICE_PER_CAN * cans * TAX)
total = round(total,2)
print 'For %d square feet, you\'ll need %d cans of paint.'
%(square_feet, cans)
print 'That will cost you \$%f.' %(total)

total = PRICE_PER_CAN * cans + (PRICE_PER_CAN * cans * TAX)
print 'For %d square feet, you\'ll need %d cans of paint.'
%(square_feet, cans)
print 'That will cost you \$%f.' %(round(total),2)
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```