Euler 26

gistfile1.txt

# we know the period of a repeating decimal p is always less than p
# so we can count down- when we find a big repeater, we save it
# and stop counting when i is less than biggest period

i = 1000
biggest_period = 0

while (i > 0):
	#compute the order of 10 modulo p
	j = 1
	while j < 1000:
		order = (10**j)%i
		if (order == 1):
#			print "1/%r terminates in %r digits" % (i,j)
			if biggest_period < j:
				biggest_i = i
				biggest_period = j
			break
		j = j + 1
	if i < biggest_period:
		break
	i = i - 1 
	
print "for p<1000, 1/%d the longest period, which is %d digits long" % (biggest_i, biggest_period)