diff --git a/lib/README.md b/lib/README.md
index 289be14..4fec321 100644
--- a/lib/README.md
+++ b/lib/README.md
@@ -5,7 +5,7 @@ To use in browser, download [`equation.min.js`](https://raw.githubusercontent.co
 
 ```javascript
 // solve
-console.log(Equation.solve('4 * lg4 ^ 3')); // 32
+console.log(Equation.solve('4 * lg(4) ^ 3')); // 32
 
 // equation
 let sphereArea = Equation.equation('4 * PI * r^2');