It wasn't a typo, it is the mnemonic (AT=@).

diff --git a/Doc/whatsnew/3.5.rst b/Doc/whatsnew/3.5.rst
index 15d7f26b27d255a7eba0812f1190f2482a6099cc..61a95a1db33b2e753abd2c99800136aada826a9b 100644 (file)
--- a/Doc/whatsnew/3.5.rst
+++ b/Doc/whatsnew/3.5.rst
@@ -147,7 +147,7 @@ PEP 465 - A dedicated infix operator for matrix multiplication
 --------------------------------------------------------------
 
 This PEP proposes a new binary operator to be used for matrix multiplication,
-called ``@``. (Mnemonic: ``@`` is ``*`` for matrices.)
+called ``@``. (Mnemonic: ``@`` is ``*`` for mATrices.)
 
 .. seealso::