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+.. highlight:: cpp
+
+.. _lang-modulo:
+
+Modulo Operator (``%``)
+=======================
+
+Calculates the `remainder <http://en.wikipedia.org/wiki/Remainder>`_
+when one integer is divided by another. It is useful for keeping a
+variable within a particular range (e.g.  the size of an array).
+
+Syntax
+------
+
+::
+
+    dividend % divisor
+
+Parameters
+----------
+
+**dividend**: the number to be divided
+
+**divisor**: the number to divide by
+
+Returns
+-------
+
+The remainder of **dividend**\ /\ **divisor**\ .
+
+Examples
+--------
+
+::
+
+    int x;
+    x = 7 % 5;   // x now contains 2
+    x = 9 % 5;   // x now contains 4
+    x = 5 % 5;   // x now contains 0
+    x = 4 % 5;   // x now contains 4
+
+::
+
+    /* update one value in an array each time through a loop */
+
+    int values[10];
+    int i = 0;
+
+    void setup() {
+        // no setup necessary
+    }
+
+    void loop() {
+      values[i] = analogRead(0);
+      i = (i + 1) % 10;   // modulo operator makes sure i stays between 0 and 9
+    }
+
+Tip
+---
+
+The modulo operator does not work on floats.  For that, you can use
+the C standard library function `fmod()
+<http://sourceware.org/newlib/libm.html#fmod>`_.
+
+See Also
+--------
+
+-  :ref:`Arithmetic <lang-arithmetic>`
+
+.. include:: /arduino-cc-attribution.txt