diff --git a/README.md b/README.md
index 376e6d8..8e3cf48 100644
--- a/README.md
+++ b/README.md
@@ -22,7 +22,7 @@ pytest tests/
 
 The following code snippet shows the basic usage of qdao. You can configure the `num_primary` parameter to reduce the memory occupation.
 
-`memory = 2^{num\_primary} * 16 \text{ Byte}`
+$\text{memory} = 2^{\text{num\_primary}} * 16 \text{ Byte}$
 
 ```Python
 from qdao import Engine