問題 The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143 ? ソース require 'mathn' x = 600851475143 pv = x.prime_division p pv[pv.size - 1][0] 解答 6857 感想 ライブラリ使って余裕！

問題 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, ... Find the sum of all the even-valued terms in the seque…

About - Project Eulerに参戦し始めた Rubyの勉強も兼ねてRubyで挑戦問題の和訳はこちらProject Euler - PukiWiki 問題 If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 2…