[Python] Python : name 'math' is not defined Error?

I am a beginner in python and cant understand why this is happening:

from math import *
print "enter the number"
n=int(raw_input())
d=2
s=0
while d<n :
if n%d==0:
x=math.log(d)
s=s+x
print d
d=d+1
print s,n,float(n)/s


Running it in Python and inputing a non prime gives the error

Traceback (most recent call last):
File "C:\Python27\mit ocw\pset1a.py", line 28, in <module>
x=math.log(d)
NameError: name 'math' is not defined

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