math.log(243,3) problem

Problem

In python:

>>> import math
>>> math.log(243,3)
4.999999999999999
# Expected: 5

Solution

1. >>> import math
   >>> math.log10(243)/math.log10(3)
   5

2. >>> import math
   >>> x = math.log(243,3)
   
   # Judge whether an int
   >>> judge = (round(x)-x) < 0.0000001
   True
   
   # get the Int value
   >>> round(x)