Floating point multiplication in python

From	xyz <xyzhtml@163.com>
Subject	Floating point multiplication in python
Date	2011-09-06 13:57 +0800
Newsgroups	comp.lang.python
Message-ID	<mailman.790.1315289581.27778.python-list@python.org> (permalink)

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hi all:

As we know ,  1.1 * 1.1 is 1.21 . 
But in python ,I got following :

>>> 1.1 * 1.1
1.2100000000000002

why python get wrong result? Who can tell me  where's the 0.0000000000000002 from?

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Floating point multiplication in python xyz <xyzhtml@163.com> - 2011-09-06 13:57 +0800
  Re: Floating point multiplication in python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-09-06 17:11 +1000
  Re: Floating point multiplication in python Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-09-06 12:14 +0200
    Re: Floating point multiplication in python Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-09-06 18:07 +0200
      Re: Floating point multiplication in python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-09-07 14:51 +1000
        Re: Floating point multiplication in python Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2011-09-06 23:35 -0700
        Re: Floating point multiplication in python Gelonida N <gelonida@gmail.com> - 2011-09-07 10:57 +0200
        Re: Floating point multiplication in python Terry Reedy <tjreedy@udel.edu> - 2011-09-07 05:37 -0400

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