You can use (.*?)(\d+)(.*)
regular expression, that will save 3 groups: everything before digits, digits and everything after:
>>> import re
>>> pattern = ur'(.*?)(\d+)(.*)'
>>> s = u"ரூ.100"
>>> match = re.match(pattern, s, re.UNICODE)
>>> print match.group(1)
ரூ.
>>> print match.group(2)
100
Or, you can unpack matched groups into variables, like this:
>>> s = u"100ஆம்"
>>> match = re.match(pattern, s, re.UNICODE)
>>> before, digits, after = match.groups()
>>> print before
>>> print digits
100
>>> print after
ஆம்
Hope that helps.