diff --git a/doc/filters/number_format.rst b/doc/filters/number_format.rst
index 564de30e6..eca99eab4 100644
--- a/doc/filters/number_format.rst
+++ b/doc/filters/number_format.rst
@@ -15,13 +15,15 @@ separator using the additional arguments:
 
     {{ 9800.333|number_format(2, '.', ',') }}
 
-To format negative numbers, wrap the number with parentheses (needed because of
+To format negative numbers or math calculation, wrap the previous statement with parentheses (needed because of
 Twig's :ref:`precedence of operators <twig-expressions>`:
 
 .. code-block:: twig
 
     {{ -9800.333|number_format(2, '.', ',') }} {# outputs : -9 #}
     {{ (-9800.333)|number_format(2, '.', ',') }} {# outputs : -9,800.33 #}
+    {{  1 + 0.2 | number_format(2) }} {# outputs : 1.2 #}
+    {{ (1 + 0.2) | number_format(2) }} {# outputs : 1.20 #}
 
 If no formatting options are provided then Twig will use the default formatting
 options of: