diff --git a/18.06-PS8.ipynb b/18.06-PS8.ipynb
index 34a83c82..4e0e382a 100644
--- a/18.06-PS8.ipynb
+++ b/18.06-PS8.ipynb
@@ -961,7 +961,7 @@
     "\n",
     "There are infinitely many possible $M$ but only one with ones and zeros.  Please find the $M$ whose entries are ones and zeros.\n",
     "\n",
-    "Format: M=[[a,b],[c,d]]"
+    "Format: M=[[a b],[c d]]"
    ]
   },
   {