diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..496ee2c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.DS_Store
\ No newline at end of file
diff --git a/euler.rb b/euler.rb
index f61fde2..5ecb019 100644
--- a/euler.rb
+++ b/euler.rb
@@ -6,14 +6,18 @@ class Integer
   end
 
   def divisors
-    divisors = []
-    (1..Math.sqrt(self).to_i).each do |num|
-      if self % num == 0
-        divisors << num
-        divisors << self / num
+    [].tap do |divisors|
+      (1..Math.sqrt(self).to_i).each do |num|
+        if self % num == 0
+          divisors << num
+          divisors << self / num
+        end
       end
     end
-    divisors
+  end
+
+  def prime_factors
+    self.prime_division.map(&:first)
   end
 
   def factorial
diff --git a/euler001.rb b/euler001.rb
index 6b02231..f06584e 100644
--- a/euler001.rb
+++ b/euler001.rb
@@ -1,9 +1,7 @@
 def multiples_of_three_and_five_below(n)
-  multiples = []
-  (3..n-1).each do |i|
-    multiples << i if ((i % 3 == 0) || (i % 5 == 0))
-  end
-  multiples
+  (3..n-1).select { |i| (i % 3 == 0) || (i % 5 == 0) }
 end
 
-puts multiples_of_three_and_five_below(1000).inject(:+)
+def solution
+  multiples_of_three_and_five_below(1000).inject(:+)
+end
diff --git a/euler002.rb b/euler002.rb
index c4f1253..9d66d54 100644
--- a/euler002.rb
+++ b/euler002.rb
@@ -1,30 +1,16 @@
-def fibonacci(n)
-  fibTable = []
-  if (n == 0) or (n == 1)
-    return 1
-  else
-    if fibTable.at(n-1) == nil
-      fibTable.insert(n-1, fibonacci(n-1))
-      fib1 = fibTable.at(n-1)
-    else
-      fib1 = fibTable.at(n-1)
+def even_fibonacci_up_to(n)
+  Enumerator.new do |y|
+    a = 0
+    b = 1
+    loop do
+      temp = b
+      b = a + b
+      a = temp
+      y << b
     end
-    if fibTable.at(n-2) == nil
-      fibTable.insert(n-2, fibonacci(n-2))
-      fib2 = fibTable.at(n-2)
-    else
-      fib2 = fibTable.at(n-2)
-    end
-    return fib1 + fib2
-  end
+  end.take_while { |i| i < n }.select { |i| i.even? }
 end
 
-sum = 0
-for i in 1..32
-  fib = fibonacci(i)
-  if (fib%2) == 0
-    sum += fib
-  end
+def solution
+  even_fibonacci_up_to(4000000).inject(:+)
 end
-
-puts sum
diff --git a/euler003.rb b/euler003.rb
index 51ac37f..834e177 100644
--- a/euler003.rb
+++ b/euler003.rb
@@ -1,38 +1,5 @@
-def sieve(n) 
-  eSieve = (2..n).to_a
-  i = 0
-  pbar = ProgressBar.new("sieving", n)
-  while i < Math.sqrt(n)
-    j = i + 1
-    while (j < eSieve.length)
-      if (eSieve[j] > (i ** 2)) and ((eSieve[j] % eSieve[i]) == 0)
-        eSieve.delete_at j
-        pbar.inc
-      end
-      j += 1
-    end
-    i += 1
-    pbar.set(i + (n-eSieve.length))
-  end
-  pbar.finish
-  eSieve
+require_relative 'euler'
+
+def solution
+  600851475143.prime_factors.max
 end
-
-eSieve = sieve(600851475143)
-
-def isPrime(n)
-  eSieve.contains(n)
-end
-
-puts isPrime(7)
-
-factors = []
-for i in 1..600851475143
-  if (600851475143 % i) == 0
-    if isPrime(600851475143 % i)
-      factors << i
-    end
-  end
-end
-
-
diff --git a/euler004.rb b/euler004.rb
index 2d7d5fe..a22d0f3 100644
--- a/euler004.rb
+++ b/euler004.rb
@@ -1,13 +1,13 @@
 require_relative 'euler'
 
 def products_of_three_digits
-  products = []
-  (100..999).each do |i|
-    (100..999).each do |j|
-      products << i*j
+  [].tap do |products|
+    (100..999).each do |i|
+      (100..999).each do |j|
+        products << i*j
+      end
     end
   end
-  products
 end
 
 def solution
diff --git a/euler005.rb b/euler005.rb
index a53732a..2a0ca51 100644
--- a/euler005.rb
+++ b/euler005.rb
@@ -1,22 +1,17 @@
 require_relative 'euler'
-require 'prime'
 
 def factorization_of_integer_divisible_by_all_integers_up_to(n)
   {}.tap do |factorization|
     (2..n).map do |i|
-      Prime.prime_division(i).map do |factor|
-        factorization[factor.first] = factor.last if (!factorization.include?(factor.first) || (factor.last > factorization[factor.first]))
+      Prime.prime_division(i).map do |prime, exponent|
+        factorization[prime] = exponent if (!factorization.include?(prime) || (exponent > factorization[prime]))
       end
     end
   end
 end
 
 def factors_to_int(factorization)
-  [].tap do |result|
-    factorization.each do |prime, exponent|
-      result << prime ** exponent
-    end
-  end.inject(:*)
+  factorization.map { |prime, exponent| prime ** exponent }.inject(:*)
 end
 
 def solution
diff --git a/euler006.rb b/euler006.rb
index e1f7d1a..d299fe5 100644
--- a/euler006.rb
+++ b/euler006.rb
@@ -6,10 +6,6 @@ def square_sums(n)
   (1..n).map { |i| i ** 2 }.inject(:+)
 end
 
-def difference(n)
-  sum_squared(n) - square_sums(n)
-end
-
 def solution
-  difference(100)
+  sum_squared(100) - square_sums(100)
 end
diff --git a/euler008.rb b/euler008.rb
index 7754ea6..ea65bd3 100644
--- a/euler008.rb
+++ b/euler008.rb
@@ -1,7 +1,7 @@
 require_relative 'euler'
 
 def largest_consecutive_product(n, adjacent)
-  n.to_digit_list.each_cons(adjacent).map { |x| x.inject(&:*) }.max
+  n.to_digit_list.each_cons(adjacent).map { |x| x.inject(:*) }.max
 end
 
 def solution
diff --git a/euler016.rb b/euler016.rb
index 6b1d2d6..7e8bfd5 100644
--- a/euler016.rb
+++ b/euler016.rb
@@ -1 +1,5 @@
-puts (2**1000).to_s.split("").map(&:to_i).inject(:+)
+require_relative 'euler'
+
+def solution
+  (2**1000).to_digit_list.inject(:+)
+end