diff --git a/Liquid-for-Designers.textile b/Liquid-for-Designers.textile
index 8a443b7..d56a88c 100644
--- a/Liquid-for-Designers.textile
+++ b/Liquid-for-Designers.textile
@@ -51,6 +51,10 @@ h3. Standard Filters
 * **truncate** - truncate a string down to x characters
 * **truncatewords** - undocumented
 * **upcase** - convert a input string to UPCASE
+* **minus** - subtracts two numbers 
+* **plus** - add to numbers
+* **times** - multiply two numbers
+* **divided_by** - divide two numbers
 
 h1. Tags