I like Fredrik's solution. If for some reason you are afraid of logarithms, you could also do:
>>> x = 4978 >>> decades = [10 ** n for n in xrange(-1,8)] >>> import itertools >>> itertools.ifilter(lambda decade: x < decade, decades).next() 10000 BTW, are the python-dev guys aware that 10 ** -1 = 0.10000000000000001 ? -- http://mail.python.org/mailman/listinfo/python-list
