diff --git a/lecture7.md b/lecture7.md
index d8b15c0d..5c34d0d4 100644
--- a/lecture7.md
+++ b/lecture7.md
@@ -615,7 +615,7 @@ $$
 0.9 & 0.0 \\\\
 0.0 & 0.2
 \end{matrix}\right) \\\\
-\mathbf{O}\_2 &= \left(\begin{matrix}
+\mathbf{O}\_3 &= \left(\begin{matrix}
 0.1 & 0.0 \\\\
 0.0 & 0.8
 \end{matrix}\right)