diff --git a/Combinations.rb b/Combinations.rb
new file mode 100644
index 0000000..518c092
--- /dev/null
+++ b/Combinations.rb
@@ -0,0 +1,12 @@
+def combinations (first, second)
+	res = []
+	first.each do |f|
+		second.each do |s|
+			res << f + s
+		end
+	end
+	return res
+end
+
+#test
+#puts combinations(["on","in"],["to","rope"])
\ No newline at end of file
diff --git a/Counting_game.rb b/Counting_game.rb
new file mode 100644
index 0000000..96b671f
--- /dev/null
+++ b/Counting_game.rb
@@ -0,0 +1,27 @@
+def next_friend(friend, count_of_friends, is_forward)
+	if is_forward
+		friend +=  1
+		friend = 1 if friend > count_of_friends
+	else
+		friend -= 1
+		friend = count_of_friends if friend == 0
+	end
+	return friend
+end
+
+def count_game_begin(count_of_friends, max_count)
+	friend = 0
+	is_forward = true	
+
+	1.upto(max_count) do |n|
+		friend = next_friend(friend, count_of_friends, is_forward)
+		
+		puts "#{friend} says #{n}" 
+		is_forward = !is_forward if n%7 == 0
+
+		friend = next_friend(friend, count_of_friends, is_forward) if n%11 == 0 
+	end
+end
+
+#test
+#count_game_begin(10, 100)
\ No newline at end of file
diff --git a/Primes.rb b/Primes.rb
new file mode 100644
index 0000000..98b4ac1
--- /dev/null
+++ b/Primes.rb
@@ -0,0 +1,12 @@
+def is_prime?(num)
+	(num/2).downto(2) do |n|
+		return false if num%n == 0
+	end
+	return true
+end
+
+#test
+#puts is_prime?(7)
+
+#test
+#puts is_prime?(14)
\ No newline at end of file
diff --git a/Rectangle_overlap.rb b/Rectangle_overlap.rb
new file mode 100644
index 0000000..42b44c9
--- /dev/null
+++ b/Rectangle_overlap.rb
@@ -0,0 +1,131 @@
+
+class Coord
+	attr_accessor :X
+	attr_accessor :Y
+end
+
+class Rectangle
+	attr_accessor :A
+	attr_accessor :B
+	def initialize(rec)
+		@A = Coord.new
+		@B = Coord.new
+		@A.X = rec[0][0]
+		@A.Y = rec[0][1]
+		@B.X = rec[1][0]
+		@B.Y = rec[1][1]
+	end
+end
+
+def order_coord_of_rectangles(rec)
+#   ------------- B 	  --------------- A   	A---------------- 	B --------------- 
+#   |		|	  |		|	|		|	  |		|	
+#   |correct	|	  |		|	|		|	  |		|
+# A ------------	B ---------------	----------------- B	  --------------- A
+	if rec.B.X < rec.A.X
+		temp = Coord.new
+		temp = rec.A
+		rec.A = rec.B
+		rec.B = temp
+	end
+
+	if rec.A.Y > rec.B.Y
+		diff = rec.A.Y - rec.B.Y
+		rec.A.Y -= diff
+		rec.B.Y += diff
+	end
+
+	return rec
+end
+
+# order the rectangles as per assumptions
+def order_rectangles(rec1, rec2)
+	r1 = Rectangle.new(rec1)
+	r2 = Rectangle.new(rec2)
+	r1 = order_coord_of_rectangles(r1)
+	r2 = order_coord_of_rectangles(r2)
+
+	if r2.A.X < r1.A.X
+		temp = r1
+		r1 = r2
+		r2 = temp
+	end
+
+	ret = [r1, r2]
+	return ret
+end
+
+def overlap?(rec1, rec2)
+	rects = order_rectangles(rec1, rec2)
+	r1 = rects[0]
+	r2 = rects[1]
+#   -------------
+#   |		|
+#   |		|
+#   -------------
+#   	-----------------
+#   	|		|
+#   	|		|
+#   	-----------------
+#------------------------------------
+#   -------------
+#   |		|
+#   |	--------|--------
+#   |	|	|	|	
+#   ----|--------	|
+#   	|		|
+#   	-----------------
+#------------------------------------
+#   ---------------------
+#   |	 |	|	|
+#   |	 |	|	|
+#   ---------------------
+#------------------------------------
+#   ---------
+#   |	----|----
+#   |	|   |	|	
+#   |	----|----
+#   ---------
+#------------------------------------
+#	    -------------
+#  	----|----	|
+#  	|   |	|	|
+#  	----|----	|
+#	    -------------
+#------------------------------------
+#       ---------
+#	|	|
+#   ----|----	|
+#   |	|   |	|
+#   |	----|----
+#   |	    |
+#   ---------
+#------------------------------------
+#	---------
+#   	|	|
+#   	|	|
+#   	---------
+#   ----------
+#   |	     |
+#   |	     |
+#   ----------
+
+	if r2.A.X < r1.B.X
+		if r1.A.Y > r2.B.Y
+			return false
+		elsif r2.A.Y > r1.B.Y
+			return false
+		else
+			return true
+		end	
+	else
+		return false	
+	end
+end
+
+
+#test assumptions: first rectangle along x-axis first and first co-ordinate along axes first for each rectangle, both co-ordinates on diagonally opposite corners
+#test: overlap is true
+#puts overlap?( [ [0,0],[3,3] ], [ [1,1],[4,5] ] )
+#test: overlap is false
+#puts overlap?( [ [0,0],[1,4] ], [ [1,1],[3,2] ] )
diff --git a/Uniques.rb b/Uniques.rb
new file mode 100644
index 0000000..8f71141
--- /dev/null
+++ b/Uniques.rb
@@ -0,0 +1,13 @@
+def uniques(uniq)
+	uniq.each_with_index do |v, i|
+		for j in (i+1).upto(uniq.length - 1)
+			if v == uniq[j]
+				uniq.delete_at(j)
+			end
+		end
+	end
+	return uniq
+end
+
+#test 
+#puts uniques([1,5,"frog", 2,1,3,"frog"])
\ No newline at end of file
diff --git a/factorial.rb b/factorial.rb
new file mode 100644
index 0000000..f4da6aa
--- /dev/null
+++ b/factorial.rb
@@ -0,0 +1,10 @@
+def factorial(n)
+	res = 1
+	(2).upto(n) do |val|
+		res *= val
+	end
+	return res
+end
+
+#test: positive integer
+#puts factorial(5)
\ No newline at end of file
diff --git a/power.rb b/power.rb
new file mode 100644
index 0000000..34762c3
--- /dev/null
+++ b/power.rb
@@ -0,0 +1,10 @@
+def power(base, exp)
+	res = 1
+	exp.times do
+		res *= base
+	end
+	return res
+end
+
+#test : positive integers
+#puts power(2, 4)
\ No newline at end of file