fourkind.py

#!/usr/bin/python

import random

total = 0;
good = 0;

for n in xrange(1,10**8):
	s = "{0:0>8}".format(n);
	a = {}
	for c in list(s):
		if c in a.keys():
			a[c]+=1;
		else:
			a[c]=1;
	if 4 in a.values():
		good+=1;

print float(good)/float(10**8)