diff --git a/README.md b/README.md
index 29e36a8..5bdd0e7 100644
--- a/README.md
+++ b/README.md
@@ -2,3 +2,5 @@ prep_ruby_challenges
 ====================
 
 [The Ruby challenge problems from the Markup and Coding course of the Viking Code School Prep Work](http://www.vikingcodeschool.com/web-markup-and-coding/level-up-your-ruby-judo)
+
+Tingting Wang
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diff --git a/combinations.rb b/combinations.rb
new file mode 100644
index 0000000..e62b977
--- /dev/null
+++ b/combinations.rb
@@ -0,0 +1,16 @@
+#Write a method combinations which takes two arrays of strings and returns an array with all of the combinations of the items in them, listing the first items first.
+
+def combinations(array1, array2)
+  combined = []
+  array1.each do |x|
+    array2.each do |y|
+      combined << x + y
+    end
+  end
+  puts combined
+end
+
+array1 = ["on", "in"]
+array2 = ["to", "rope", "something"]
+
+combinations(array1, array2)
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diff --git a/countinggame.rb b/countinggame.rb
new file mode 100644
index 0000000..c2a94fe
--- /dev/null
+++ b/countinggame.rb
@@ -0,0 +1,33 @@
+def countinggame(number_of_players, number)
+  current_player = 1
+  current_number = 1
+  direction = 1
+
+  while current_number < number
+
+    current_number += 1
+    current_player += 1*direction
+      if current_number % 7 == 0
+        direction *= -1
+      elsif current_number % 11 == 0
+        current_player += 1*direction
+      end
+
+    if current_player > number_of_players
+      current_player = (current_player - number_of_players)
+    elsif current_player < 1
+      current_player = (current_player + number_of_players)
+    end
+
+  end
+
+puts current_player
+end
+
+countinggame(10, 100)
+
+
+
+
+
+
diff --git a/factorial.rb b/factorial.rb
new file mode 100644
index 0000000..7e0e0ac
--- /dev/null
+++ b/factorial.rb
@@ -0,0 +1,12 @@
+#Write a method factorial which takes a number and returns the product of every number up to the current number multiplied together.
+
+def factorial n
+  product = 1
+  while n > 0
+    product = product * n
+    n -= 1
+  end
+  puts product
+end
+
+factorial(77)
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diff --git a/overlap.rb b/overlap.rb
new file mode 100644
index 0000000..2023564
--- /dev/null
+++ b/overlap.rb
@@ -0,0 +1,31 @@
+#Write a method overlap which takes two rectangles defined by the coordinates of their corners, e.g. [[0,0],[3,3]] and [[1,1],[4,6]], and determines whether they overlap. You can assume all coordinates are positive integers.
+
+def overlap(rectangle1, rectangle2)
+
+horizontal_overlap = false
+vertical_overlap = false
+
+  (rectangle1[0][0]...rectangle1[1][0]).each do |x|
+    if (rectangle2[0][0]...rectangle2[1][0]).include?(x)
+      horizontal_overlap = true
+    end
+  end
+
+  (rectangle1[0][1]...rectangle1[1][1]).each do |y|
+    if (rectangle2[0][1]...rectangle2[1][1]).include?(y)
+      vertical_overlap = true
+    end
+  end
+
+  if horizontal_overlap == true && vertical_overlap == true
+    puts "overlap"
+  else
+    puts "no overlap"
+  end
+
+end
+
+rectangle1 = [[0,0],[3,3]]
+rectangle2 = [[1,1],[4,5]]
+
+overlap(rectangle1, rectangle2)
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diff --git a/power.rb b/power.rb
new file mode 100644
index 0000000..cc800a9
--- /dev/null
+++ b/power.rb
@@ -0,0 +1,12 @@
+#Write a method power which takes two integers (base and exponent) and returns the base raised to the power of exponent. Do not use Ruby’s ** operator for this!
+
+def power(base, exponent)
+  base_product = 1
+  while exponent > 0
+    base_product *= base
+    exponent -= 1
+  end
+  puts base_product
+end
+
+puts power(4, 0)
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diff --git a/primes.rb b/primes.rb
new file mode 100644
index 0000000..cf9cdb5
--- /dev/null
+++ b/primes.rb
@@ -0,0 +1,14 @@
+#Write a method is_prime? which takes in a number and returns true if it is a prime number.
+
+def is_prime?(n)
+  (2...n).each do |x|
+    if n % x == 0
+      false
+    end
+  end
+  puts "true"
+  true
+end
+
+
+is_prime?(7)
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diff --git a/uniques.rb b/uniques.rb
new file mode 100644
index 0000000..b6c3db0
--- /dev/null
+++ b/uniques.rb
@@ -0,0 +1,13 @@
+#Write a method uniques which takes an array of items and returns the array without any duplicates. Don’t use Ruby’s uniq method!
+
+def uniques(array)
+  unique_array = []
+  array.each do |x|
+    unique_array << x unless unique_array.include?(x)
+  end
+  puts unique_array
+end
+
+random = [1, 2, 3, "dog", 3, 2, 1, 3, 5, 6, 7, 8, 8, 8]
+
+uniques(random)
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