075-golden-ratio-obsession.md

75 - Golden Ratio Obsession

Written by Austin Zhou

Problem

Find the Number of Digits in the 16th Fibonacci Number that Contains 1618 and is Divisible by 1618.

Hint

Use your knowledge from the previous basic python problems! (You are not, however, limited to python for this problem - you can compute the answer in any language you'd like.)

Solution

Using your python knowledge from python basics it should be easy to write a brute force algorithm.

def fib():
	a = 1
	b = 1
	while True:
		a,b = a+b,a
		yield a
count = 0
for i in fib():
	if "1618" in str(i) and i%1618==0:
		count+=1
	if count == 16:
		print len(str(i))
		break

This should yield the number 7092 and that is your flag.

Flag

7092