# Euler Problem 2: Even Fibonacci Numbers

**The Devil is in the Data**, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)

Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

## Euler Problem 2 Definition

*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:*

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

## Solution

The code generates Fibonacci numbers until it reaches the value of four million. The code then sums the even numbers in the sequence.

fib <- c(1, 2) #Define first two numbers while (max(fib) < 4e+06) { # Generate Fibonacci numbers until limit is reached len <- length(fib) fib <- c(fib, fib[len - 1] + fib[len]) } answer <- sum(fib[fib%%2 == 0])

A range of packages exists that generate Fibonacci numbers. The *gmp* package for Multiple Precision Arithmetic and the numbers package supplies functions to calculate the n^{th} Fibonacci number. This package is also able to work with very large numbers.

library(gmp) i <- 1 answer <- 0 fib <- fibnum(1) while (fibnum(i) <= 4e6) { fib <- fibnum(i) if (fib%%2==0) answer <- answer + fib i <- i + 1 } print(answer)

## Fibonacci Numbers as a magic trick

Fibonacci numbers describe many natural processes and can also be used to create magic tricks. The Missing Square Puzzle is based on this principle.

The post Euler Problem 2: Even Fibonacci Numbers appeared first on The Devil is in the Data.

**leave a comment**for the author, please follow the link and comment on their blog:

**The Devil is in the Data**.

R-bloggers.com offers

**daily e-mail updates**about R news and tutorials about learning R and many other topics. Click here if you're looking to post or find an R/data-science job.

Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.