# Project Euler: Problem #2 – Even Fibonacci Numbers

Today I started a Project Euler account and began working through a few of the problems. They are really fun problems! I highly recommend starting an account if you haven’t already, it’s free anyways…

### Description

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, …

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

The solution is really basic, and Python makes the solution elegant. Simply perform the basic Fibonacci Sequence, namely

$F_{n} = F_{n-1} + F_{n-2}$

where $F_{0} = 0$ and $F_{1}=1$.

To ensure that only the even numbers in the sequence are added to the sum, I simply add an if statement that only evaluates to true when the left hand operand can be divided by two evenly. Here’s my solution, tell me what you think.

```def sum_even_fib(n):
sum = 0
a, b = 0, 1
while b < n:
a, b = b, a + b
if b % 2 == 0:
sum = sum + b
return sum

print(sum_even_fib(4000000))```