[root@wyq-vserver-vm-master ~]# python
Python 2.6.6 (r266:84292, Jun  3 2012, 00:16:45) 
[GCC 4.4.6 20110731 (Red Hat 4.4.6-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> a=3.4
>>> a
3.3999999999999999   #输出不正常
>>> b=2
>>> b
2
>>> a*b
6.7999999999999998   #输出不正常
>>> print a*b
6.8                  #输出正常并且数值正确
>>>