diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 000000000..c285c09f5
Binary files /dev/null and b/.DS_Store differ
diff --git a/00_hello/hello.rb b/00_hello/hello.rb
new file mode 100644
index 000000000..3623e57f4
--- /dev/null
+++ b/00_hello/hello.rb
@@ -0,0 +1,7 @@
+def hello
+  "Hello!"
+end
+
+def greet(who)
+  "Hello, #{who}!"
+end
\ No newline at end of file
diff --git a/01_temperature/temperature.rb b/01_temperature/temperature.rb
new file mode 100644
index 000000000..ff3f0055e
--- /dev/null
+++ b/01_temperature/temperature.rb
@@ -0,0 +1,9 @@
+def ftoc(fahrenheit)
+  c = (fahrenheit - 32).to_f * 5/9
+  return c
+end
+
+def ctof(celcius)
+  f = (celcius.to_f * 9/5) + 32
+  return f
+end
\ No newline at end of file
diff --git a/02_calculator/calculator.rb b/02_calculator/calculator.rb
new file mode 100644
index 000000000..aa8ec5479
--- /dev/null
+++ b/02_calculator/calculator.rb
@@ -0,0 +1,37 @@
+def add(a,b)
+  a + b
+end
+
+def subtract(a,b)
+  a - b
+end
+
+def sum(array)
+  sum = 0
+  array.each do |i|
+    sum += i
+  end
+  sum
+end
+
+def multiply(array)
+  product = 1
+  array.each do |i|
+    product *= i
+  end
+  product
+end
+
+def power(a,b)
+  a**b
+end
+
+def factorial(n)
+  if n == 1
+    return 1
+  elsif n == 0
+    return 0
+  else
+    n * factorial(n - 1)
+  end
+end
\ No newline at end of file
diff --git a/02_calculator/calculator_spec.rb b/02_calculator/calculator_spec.rb
index fef7e9d00..4e9f731ba 100644
--- a/02_calculator/calculator_spec.rb
+++ b/02_calculator/calculator_spec.rb
@@ -79,21 +79,41 @@
 
 describe "#multiply" do
 
-  it "multiplies two numbers"
+  it "multiplies two numbers" do
+    expect(multiply([2,8])).to eq(16)
+  end
 
-  it "multiplies several numbers"
+  it "multiplies several numbers" do
+    expect(multiply([2,5,3,4])).to eq(120)
+  end
   
 end
 
 describe "#power" do
-  it "raises one number to the power of another number"
+  it "raises one number to the power of another number" do
+    expect(power(5,3)).to eq(125)
+  end
 end
 
 # http://en.wikipedia.org/wiki/Factorial
 describe "#factorial" do
-  it "computes the factorial of 0"
-  it "computes the factorial of 1"
-  it "computes the factorial of 2"
-  it "computes the factorial of 5"
-  it "computes the factorial of 10"
+  it "computes the factorial of 0" do
+    expect(factorial(0)).to eq(0)
+  end
+
+  it "computes the factorial of 1" do
+    expect(factorial(1)).to eq(1)
+  end
+
+  it "computes the factorial of 2" do
+    expect(factorial(2)).to eq(2)
+  end
+
+  it "computes the factorial of 5" do
+    expect(factorial(5)).to eq(120)
+  end
+
+  it "computes the factorial of 10" do
+    expect(factorial(10)).to eq(3628800)
+  end
 end
diff --git a/03_simon_says/simon_says.rb b/03_simon_says/simon_says.rb
new file mode 100644
index 000000000..79fd0126a
--- /dev/null
+++ b/03_simon_says/simon_says.rb
@@ -0,0 +1,40 @@
+def echo(str)
+  str
+end
+
+def shout(str)
+  str.upcase
+end
+
+def repeat(str, num = 2)
+  phrase = ""
+  until num == 0
+    phrase += str
+    phrase += " "
+    num -= 1
+  end
+  phrase.strip
+end
+
+def start_of_word(word,num_letters)
+  word.slice(0, num_letters)
+end
+
+def first_word(str)
+  str.split(' ').first
+end
+
+def titleize(str)
+  small_word = ['and','over','the']
+  str_array = str.split(' ')
+  str_array.each_with_index do |i, index|
+    if index == 0
+      i.capitalize!
+    elsif small_word.include?(i)
+      i
+    else
+      i.capitalize!
+    end
+  end
+  str_array.join(' ')
+end
\ No newline at end of file
diff --git a/04_pig_latin/pig_latin.rb b/04_pig_latin/pig_latin.rb
new file mode 100644
index 000000000..df79c1348
--- /dev/null
+++ b/04_pig_latin/pig_latin.rb
@@ -0,0 +1,61 @@
+require 'pry'
+def translate(str)
+
+  str.downcase!
+  # split string into words
+  words = split_str(str)
+
+  # split word into letters
+  letters = split_words(words)
+
+  # until reach a vowel (unless qu), unshift consonants
+  # and push those consonants to an end_of_word array
+  # append the end_of_word array to the array
+  # append the 'ay' array to the array
+  pig_latinned_arrays = move_consonants(letters)
+
+  # join the letters array
+  # join the word array
+  # return the array
+  pig_latinned_string = join_arrays(pig_latinned_arrays)
+  return pig_latinned_string
+
+end
+
+def split_str(str)
+  str.split(' ')
+end
+
+def split_words(words)
+  letters = words.map do |word|
+    word.split('')
+  end
+  letters
+end
+
+def move_consonants(letters)
+  vowels = ['a','e','i','o','u']
+  ay = ['a','y']
+  letters.each do |word|
+      consonants_array = []
+    until vowels.include?(word[0])
+      if word[0] == 'q' && word[1] == 'u'
+        2.times do |i|
+          consonants_array << word.shift
+        end
+      else
+        consonants_array << word.shift
+      end        
+    end
+    word.concat(consonants_array).concat(ay)
+  end
+  letters
+end
+
+def join_arrays(pig_latinned_arrays)
+  joined_words = []
+  pig_latinned_arrays.each do |word|
+    joined_words << word.join('')
+  end
+  joined_words.join(' ')
+end
\ No newline at end of file
diff --git a/05_silly_blocks/silly_blocks.rb b/05_silly_blocks/silly_blocks.rb
new file mode 100644
index 000000000..716edea94
--- /dev/null
+++ b/05_silly_blocks/silly_blocks.rb
@@ -0,0 +1,19 @@
+def reverser
+  split_string = yield.split(' ')
+  split_string.map do |word|
+    word.reverse!
+  end
+  result = split_string.join(' ')
+  result
+end
+
+def adder(num = 1)
+  result = yield + num
+  result
+end
+
+def repeater(num = 1)
+  num.times do |i|
+    yield
+  end
+end
\ No newline at end of file
diff --git a/06_performance_monitor/performance_monitor.rb b/06_performance_monitor/performance_monitor.rb
new file mode 100644
index 000000000..4e8edb5b1
--- /dev/null
+++ b/06_performance_monitor/performance_monitor.rb
@@ -0,0 +1,8 @@
+def measure(num_loops = 1)
+  start_time = Time.now
+  num_loops.times do
+    yield
+  end
+  end_time = Time.now
+  (end_time - start_time) / num_loops
+end
\ No newline at end of file
diff --git a/07_hello_friend/friend.rb b/07_hello_friend/friend.rb
new file mode 100644
index 000000000..68c4506ca
--- /dev/null
+++ b/07_hello_friend/friend.rb
@@ -0,0 +1,9 @@
+class Friend
+  def greeting(who = nil)
+    if who == nil
+      "Hello!"
+    else
+      "Hello, #{who}!"
+    end
+  end
+end
\ No newline at end of file
diff --git a/08_book_titles/book.rb b/08_book_titles/book.rb
new file mode 100644
index 000000000..8465db206
--- /dev/null
+++ b/08_book_titles/book.rb
@@ -0,0 +1,21 @@
+class Book
+
+  def title=(title)
+    lowercase_words = ['the','a','an','and','in','of']
+    word_array = title.split(' ')
+    word_array.map do |word|
+      if lowercase_words.include?(word)
+        word
+      else
+        word.capitalize!
+      end
+    end
+    word_array[0].capitalize!
+    @title = word_array.join(' ')
+  end
+
+  def title
+    @title
+  end
+
+end
\ No newline at end of file
diff --git a/09_timer/timer.rb b/09_timer/timer.rb
new file mode 100644
index 000000000..55a0f2a53
--- /dev/null
+++ b/09_timer/timer.rb
@@ -0,0 +1,46 @@
+
+# what we're trying to do here is create an object "Timer" with a seconds method that takes the number of seconds elapsed, and a time_string method that returns in hour: minute: second format
+
+require 'pry'
+
+class Timer
+
+  def initialize(s = 0, m = 0, h = 0)
+    @seconds = s
+    @minutes = m
+    @hours = h
+  end
+
+  def seconds
+    @seconds
+  end
+
+  def seconds=(number)
+    @seconds = number
+  end
+
+  def time_string
+    calculate_clock_time
+    make_time_read_friendly
+  end
+
+end
+
+def calculate_clock_time
+  if @seconds > 60
+    @minutes = @seconds / 60
+    @seconds -= @minutes * 60
+  end
+  if @minutes > 60
+    @hours = @minutes / 60
+    @minutes -= @hours * 60
+  end
+end
+
+def make_time_read_friendly
+  time_array = [@hours.to_s,@minutes.to_s,@seconds.to_s]
+  time_array.map do |time|
+    time.prepend('0') until time.length == 2
+  end
+  time_array.join(':')
+end
\ No newline at end of file
diff --git a/10_temperature_object/temperature.rb b/10_temperature_object/temperature.rb
new file mode 100644
index 000000000..b5c3ede1f
--- /dev/null
+++ b/10_temperature_object/temperature.rb
@@ -0,0 +1,45 @@
+require 'pry'
+class Temperature
+
+  def initialize(temperatures = {:f => nil, :c => nil })
+    @fahrenheit = temperatures[:f]
+    @celsius = temperatures[:c]
+  end
+
+  def in_fahrenheit
+    if @fahrenheit
+      @fahrenheit
+    else
+      (@celsius.to_f * 9/5).to_f + 32.to_f
+    end
+  end
+
+  def in_celsius
+    if @celsius
+      @celsius
+    else
+      (@fahrenheit.to_f - 32).to_f * 5/9.to_f
+    end
+  end
+
+  def self.from_celsius(c)
+    self.new(:c => c)
+  end
+
+  def self.from_fahrenheit(f)
+    self.new(:f => f)
+  end
+
+end
+
+class Celsius < Temperature
+  def initialize(c)
+    @celsius = c
+  end
+end
+
+class Fahrenheit < Temperature
+  def initialize(f)
+    @fahrenheit = f
+  end
+end
diff --git a/11_dictionary/dictionary.rb b/11_dictionary/dictionary.rb
new file mode 100644
index 000000000..b8196efe2
--- /dev/null
+++ b/11_dictionary/dictionary.rb
@@ -0,0 +1,59 @@
+require 'pry'
+
+class Dictionary
+
+  def initialize
+    @entries = {}
+  end  
+
+  def entries
+    @entries
+  end
+
+  def add(new_entries)
+    if new_entries.class == String
+      @entries[new_entries] = nil
+    else
+      new_entries.each do |word, definition|
+        @entries[word] = definition
+      end
+    end
+  end
+
+  def keywords
+    @entries.keys.sort
+  end
+
+  def include?(keyword)
+    return true if @entries.keys.include?(keyword)
+    false
+  end
+
+  def find(string)
+    if @entries.keys.grep(/#{string}/).empty?
+      {}
+    else
+      key_array = []
+      @entries.keys.each do |key|
+        if key =~ /#{string}/
+          key_array << key
+        end
+      end
+      result = { }
+      key_array.each do |key|
+        result.store(key,@entries[key]) 
+      end
+      result
+    end
+  end
+
+  def printable
+    print_version = ""
+    @entries.sort.each do |key, value|
+      print_version += "[#{key}] \"#{value}\"\n"
+    end
+    print_version.chomp
+  end
+
+end
+
diff --git a/12_rpn_calculator/rpn_calculator.rb b/12_rpn_calculator/rpn_calculator.rb
new file mode 100644
index 000000000..b42a8b24b
--- /dev/null
+++ b/12_rpn_calculator/rpn_calculator.rb
@@ -0,0 +1,93 @@
+require 'pry'
+
+class RPNCalculator
+
+  def initialize
+    @int_stack = []
+  end
+
+  def push(n)
+    @int_stack << n
+  end
+
+  def plus
+    if @int_stack.size >= 2
+      num_1 = @int_stack.pop
+      num_2 = @int_stack.pop
+      num_3 = num_1 + num_2
+      @int_stack.push(num_3)
+    else
+      raise "calculator is empty"
+    end
+  end
+
+  def minus
+    if @int_stack.size >= 2
+      num_1 = @int_stack.pop
+      num_2 = @int_stack.pop
+      num_3 = num_2 - num_1
+      @int_stack.push(num_3)
+    else
+      raise "calculator is empty"
+    end   
+  end
+
+  def divide
+    if @int_stack.size >= 2
+      num_1 = @int_stack.pop.to_f
+      num_2 = @int_stack.pop.to_f
+      num_3 = num_2 / num_1
+      @int_stack.push(num_3)
+    else
+      raise "calculator is empty"
+    end 
+  end
+
+  def times
+    if @int_stack.size >= 2
+      num_1 = @int_stack.pop.to_f
+      num_2 = @int_stack.pop.to_f
+      num_3 = num_1 * num_2
+      @int_stack.push(num_3)
+    else
+      raise "calculator is empty"
+    end
+  end
+
+  def tokens(str)
+    math_operators = ['+','*','-','/']
+    split_str = str.split(' ')
+    split_str.map! do |i|
+      if math_operators.include?(i)
+        i.to_sym
+      else 
+        i.to_i
+      end
+    end
+    split_str
+  end
+
+  def evaluate(str)
+    token_array = tokens(str)
+    token_array.each do |i|
+      case i
+      when :*
+        times
+      when :+
+        plus
+      when :-
+        minus
+      when :/
+        divide
+      else
+        push(i)
+      end
+    end
+    value
+  end
+
+  def value
+    @int_stack[-1]
+  end
+
+end
\ No newline at end of file
diff --git a/14_array_extensions/array_extensions.rb b/14_array_extensions/array_extensions.rb
new file mode 100644
index 000000000..aaac07cc3
--- /dev/null
+++ b/14_array_extensions/array_extensions.rb
@@ -0,0 +1,24 @@
+class Array
+
+  def sum
+    result = 0
+    self.each do |i|
+      result += i
+    end
+    result
+  end
+
+  def square
+    result = []
+    self.map do |i|
+      result << i * i
+    end
+    result
+  end
+
+  def square!
+    self.map! do |i|
+      i * i
+    end
+  end
+end
\ No newline at end of file
diff --git a/15_in_words/in_words.rb b/15_in_words/in_words.rb
new file mode 100644
index 000000000..6e99487a9
--- /dev/null
+++ b/15_in_words/in_words.rb
@@ -0,0 +1,143 @@
+require 'pry'
+
+class Fixnum
+
+  def in_words
+    @@num_string = ""
+    num = self
+    @@num_array = num.to_s.delete('_').split('')
+    size_checker
+  end
+
+  private
+
+  def size_checker
+    case @@num_array.length
+    when 1
+      ones
+    when 2
+      tens
+    when 3
+      hundreds
+    when 4..6
+      thousands
+    when 7..9
+ 
+      millions
+    when 10..12
+      billions
+    when 13..15
+      trillions
+    end
+    size_checker until @@num_array.empty?
+    @@num_string.strip
+  end
+
+  def ones
+    ones_hash = { 0 => 'zero', 1 => 'one', 2 => 'two', 3 => 'three', 4 => 'four', 5 => 'five', 6 => 'six', 7 => 'seven', 8 => 'eight', 9 => 'nine' }
+    @@num_string += " " + ones_hash[@@num_array.shift.to_i]
+  end
+
+  def tens
+    if @@num_array.slice(0,2).join('').to_i >= 20
+      above_twenty
+    else
+      teens
+    end
+  end
+
+  def teens
+    teens_hash = { 10 => 'ten', 11 => 'eleven', 12 => 'twelve', 13 => 'thirteen', 14 => 'fourteen', 15 => 'fifteen', 16 => 'sixteen', 17 => 'seventeen', 18 => 'eighteen', 19 => 'nineteen'}
+    @@num_string += " " + teens_hash[@@num_array.slice(0,2).join('').to_i]
+    @@num_array.shift(2)
+  end
+
+  def above_twenty
+    tens_hash = { 20 => 'twenty', 30 => 'thirty', 40 => 'forty', 50 => 'fifty', 60 => 'sixty', 70 => 'seventy', 80 => 'eighty', 90 => 'ninety'}
+    if @@num_array.slice(0,2).join('').to_i % 10 != 0
+      n = @@num_array.shift + "0"
+      @@num_string += " " + tens_hash[n.to_i]
+    else
+      @@num_string += " " + tens_hash[@@num_array.slice(0,2).join('').to_i]
+      @@num_array.shift(2)
+    end
+  end
+
+  def hundreds
+    hundreds_hash = { 100 => 'one hundred', 200 => 'two hundred', 300 => 'three hundred', 400 => 'four hundred', 500 => 'five hundred', 600 => 'six hundred', 700 => 'seven hundred', 800 => 'eight hundred', 900 => 'nine hundred'}
+    if @@num_array.slice(0,3).join('').to_i % 100 != 0
+      n = @@num_array.shift + "00"
+      @@num_string += " " + hundreds_hash[n.to_i]
+    else
+      @@num_string += hundreds_hash[@@num_array.join('').to_i]
+      @@num_array.shift(3)
+    end
+  end
+
+  def thousands
+    while @@num_array.length >= 4 
+      if @@num_array.length == 4
+        ones
+      elsif @@num_array.length == 5
+        tens
+      else
+        hundreds
+      end
+    end
+    @@num_string += " " + 'thousand'
+    while @@num_array[0] == "0"
+
+      @@num_array.delete_at(0)
+    end
+  end
+
+  def millions
+    while @@num_array.length >= 7 
+      if @@num_array.length == 7
+        ones
+      elsif @@num_array.length == 8
+        tens
+      else
+        hundreds
+      end
+    end
+    @@num_string += " " + 'million'
+    while @@num_array[0] == "0"
+      @@num_array.delete_at(0)
+    end
+  end
+
+  def billions
+    while @@num_array.length >= 10 
+      if @@num_array.length == 10
+        ones
+      elsif @@num_array.length == 11
+        tens
+      else
+        hundreds
+      end
+    end
+    @@num_string += " " + 'billion'
+    while @@num_array[0] == "0"
+      @@num_array.delete_at(0)
+    end
+  end
+
+  def trillions
+    while @@num_array.length >= 13 
+      if @@num_array.length == 13
+        ones
+      elsif @@num_array.length == 14
+        tens
+      else
+        hundreds
+      end
+    end
+    @@num_string += " " + 'trillion'
+    while @@num_array[0] == "0"
+      @@num_array.delete_at(0)
+    end
+  end
+
+end
+