diff --git a/module1/test_markdown.md b/module1/test_markdown.md
index c963f262157fe65a484bd5510d7f5f4d5d2a63c5..a0483ad5305081c3c6cba0106cf6b76e43133d60 100644
--- a/module1/test_markdown.md
+++ b/module1/test_markdown.md
@@ -6,3 +6,5 @@ $$\Gamma$
 $$\pi$
 
 $\cos$
+
+cette expression $\sum_{i=1}^n x_i$