diff --git a/docs/reference/arithmetic/abs.md b/docs/reference/arithmetic/abs.md
index 0fd9640d2..bd0f7a629 100644
--- a/docs/reference/arithmetic/abs.md
+++ b/docs/reference/arithmetic/abs.md
@@ -25,6 +25,8 @@ Number | BigNumber | Complex | Array | Matrix | Absolute val
 ## Examples
 
 ```js
+var math = mathjs();
+
 math.abs(3.5);                // returns Number 3.5
 math.abs(-4.2);               // returns Number 4.2
 
diff --git a/docs/reference/arithmetic/add.md b/docs/reference/arithmetic/add.md
index 4f1eb44c7..4a4bd8dd7 100644
--- a/docs/reference/arithmetic/add.md
+++ b/docs/reference/arithmetic/add.md
@@ -26,6 +26,8 @@ Number | BigNumber | Complex | Unit | String | Array &#
 ## Examples
 
 ```js
+var math = mathjs();
+
 math.add(2, 3);               // returns Number 5
 
 var a = math.complex(2, 3);
diff --git a/docs/reference/arithmetic/divide.md b/docs/reference/arithmetic/divide.md
index 2f8f068c7..3b621938d 100644
--- a/docs/reference/arithmetic/divide.md
+++ b/docs/reference/arithmetic/divide.md
@@ -26,6 +26,8 @@ Number | BigNumber | Complex | Unit | Array | Matrix |
 ## Examples
 
 ```js
+var math = mathjs();
+
 math.divide(2, 3);            // returns Number 0.6666666666666666
 
 var a = math.complex(5, 14);
diff --git a/docs/reference/arithmetic/multiply.md b/docs/reference/arithmetic/multiply.md
index 546aae0d7..b9d25da3e 100644
--- a/docs/reference/arithmetic/multiply.md
+++ b/docs/reference/arithmetic/multiply.md
@@ -26,6 +26,8 @@ Number | BigNumber | Complex | Unit | Array | Matrix |
 ## Examples
 
 ```js
+var math = mathjs();
+
 math.multiply(4, 5.2);        // returns Number 20.8
 
 var a = math.complex(2, 3);
diff --git a/docs/reference/arithmetic/subtract.md b/docs/reference/arithmetic/subtract.md
index 37e62b88a..4f32ae368 100644
--- a/docs/reference/arithmetic/subtract.md
+++ b/docs/reference/arithmetic/subtract.md
@@ -26,6 +26,8 @@ Number | BigNumber | Complex | Unit | Array | Matrix |
 ## Examples
 
 ```js
+var math = mathjs();
+
 math.subtract(5.3, 2);        // returns Number 3.3
 
 var a = math.complex(2, 3);