#13730 grammar fix

Doc/library/decimal.rst

@@ -29,7 +29,7 @@ arithmetic.  It offers several advantages over the :class:`float` datatype:
   people learn at school." -- excerpt from the decimal arithmetic specification.
 
 * Decimal numbers can be represented exactly.  In contrast, numbers like
-  :const:`1.1` and :const:`2.2` do not have an exact representations in binary
+  :const:`1.1` and :const:`2.2` do not have exact representations in binary
   floating point. End users typically would not expect ``1.1 + 2.2`` to display
   as :const:`3.3000000000000003` as it does with binary floating point.