diff --git a/docs/ch9/0-231-0-516-0-253.md b/docs/ch9/0-231-0-516-0-253.md
deleted file mode 100644
index 9316a2b..0000000
--- a/docs/ch9/0-231-0-516-0-253.md
+++ /dev/null
@@ -1,2 +0,0 @@
-# 0.231 0.516 0.253
-