diff --git a/README.md b/README.md
index 117858a..9b883c6 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,5 @@
 fizzbuzz [![Build Status](https://travis-ci.org/ituring/fizzbuzz.png)](https://travis-ci.org/ituring/fizzbuzz)
 
 本仓库供本书读者参考用，不接收任何形式的Pull Request，敬请谅解。
+
+Pull request 请到 https://github.com/ituring/first-pr 。
diff --git a/fizzbuzz.rb b/fizzbuzz.rb
new file mode 100644
index 0000000..f77910c
--- /dev/null
+++ b/fizzbuzz.rb
@@ -0,0 +1,13 @@
+class Fizzbuzz
+    def calculate number 
+        if number % 3 == 0 && number % 5 == 0
+            'fizzbuzz'
+        elsif number % 3 == 0
+            'fizz'  
+        elsif number % 5 == 0    
+            'buzz'
+        else
+            number 
+        end
+    end 
+end   
\ No newline at end of file