ProjectEuler 3 Ruby
#!/usr/bin/ruby #ans 1 a=600851475143 i=2 while i<a a /= i while a%i==0 i += 1 end p a #ans 2 a=600851475143;(2..a).each{|i|i<a or break;a/=i while a%i==0};p a #ans 3 require "mathn";p 600851475143.prime_division.last[0]
#!/usr/bin/ruby #ans 1 a=600851475143 i=2 while i<a a /= i while a%i==0 i += 1 end p a #ans 2 a=600851475143;(2..a).each{|i|i<a or break;a/=i while a%i==0};p a #ans 3 require "mathn";p 600851475143.prime_division.last[0]