[issue22917] Calculating problem

[heme]

New submission from heme:

Hi guys 

I am very new to this, (just started my first lines today) so I am using
a book to learn Python. BUT there is something wrong: 

This is my program (from the book): 

# This is not quite true outside of USA
# and is based on my dim memories of my younger years
print("Firstish Grade")
print("1 + 1 =", 1 + 1)
print("2 + 4 =", 2 + 4)
print("5 - 2 =", 5 - 2)
print()
print("Thirdish Grade")
print("243 - 23 =", 243 - 23)
print("12 * 4 =", 12 * 4)
print("12 / 3 =", 12 / 3)
print("13 / 3 =", 13 // 3, "R", 13 % 3)
print()
print("Junior High")
print("123.56 - 62.12 =", 123.56 - 62.12)
print("(4 + 3) * 2 =", (4 + 3) * 2)
print("4 + 3 * 2 =", 4 + 3 * 2)
print("3 ** 2 =", 3 ** 2) 

and this is the programs answer: 

Python 3.4.2 (v3.4.2:ab2c023a9432, Oct 6 2014, 22:15:05) [MSC v.1600 32
bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>> 
Firstish Grade
1 + 1 = 2
2 + 4 = 6
5 - 2 = 3

Thirdish Grade
243 - 23 = 220
12 * 4 = 48
12 / 3 = 4.0
13 / 3 = 4 R 1

Junior High
123.56 - 62.12 = 61.440000000000005
(4 + 3) * 2 = 14
4 + 3 * 2 = 10
3 ** 2 = 9
>>> 

As you can see, 

print("123.56 - 62.12 =", 123.56 - 62.12) is not = 61.440000000000005 

so my guess is that the interpreter has a malfunction. 

My pc is a compaq mini 110 running (walking;-)) windows xp srv pack 3 

in a std. config. 

brg 

Henning Mentz - Denmark

----------
messages: 231527
nosy: heme
priority: normal
severity: normal
status: open
title: Calculating problem

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue22917>
_______________________________________