When i type in the below in python i got the outputs as shown:
>>> a=1/3
>>> b=1/3
>>> c=1/3
>>> d=a+b+c
>>> d
1.0
>>> f=1-(1/3)-(2/3)
>>> f
1.1102230246251565e-16
>>> g=1-(1/3+2/3)
>>> g
0.0
>>>
if d
value is 1.0
and g
is 0.0
then why f
value is not 0.0
?