diff --git a/recursion-writing.rb b/recursion-writing.rb
new file mode 100644
index 0000000..72091e0
--- /dev/null
+++ b/recursion-writing.rb
@@ -0,0 +1,62 @@
+def factorial(n)
+  raise ArgumentError.new("n must be >= to 0") if n < 0
+  if n == 0
+    return 1
+  else
+    return n * factorial(n-1)
+  end
+end
+
+def reverse(s)
+  if s.length == 1
+    return s
+  else
+    return reverse(s[1..-1]) + s[0]
+  end
+end
+
+def bunny(n)
+  raise ArgumentError.new("n must be >= to 0") if n < 0
+  if n == 0
+    return 0
+  else
+    return 2 + bunny(n-1)
+  end
+end
+
+def nested(s) # better way to write this method?
+  # return false once, will always be false
+  if s == "()" || s == ""
+    return true
+  elsif s[0] == ")" || s[-1] == "("
+    return false
+  else
+    closed_index = 0
+    until s[closed_index] == ")"
+      break if closed_index == s.length - 1
+      closed_index += 1
+    end
+      return nested(s[0] + s[closed_index]) && nested(s[1...closed_index] + s[(closed_index+1)...s.length])
+  end
+end
+
+def fib(n)
+  raise ArgumentError.new("n must be >= 0") if n < 0
+  if n == 0
+    return 0
+  elsif n == 1
+    return 1
+  else
+    return fib(n-1) + fib(n-2)
+  end
+end
+
+def pal(s)
+  if s.length == 1
+    return true
+  elsif s[0] != s[-1]
+    return false
+  else
+    return pal(s[1..-2])
+  end
+end