diff --git a/01_Day_JavaScript_Refresher/01_javascript_refresher.md b/01_Day_JavaScript_Refresher/01_javascript_refresher.md
index 7d03fb4..fadc0e1 100644
--- a/01_Day_JavaScript_Refresher/01_javascript_refresher.md
+++ b/01_Day_JavaScript_Refresher/01_javascript_refresher.md
@@ -3187,7 +3187,7 @@ Destructuring function parameter
 ```js
 const rectangle = { width: 20, height: 10 }
 const calcualteArea = ({ width, height }) => width * height
-const calculatePerimeter = ({ width, height } = 2 * (width + height))
+const calculatePerimeter = ({ width, height }) => 2 * (width + height)
 ```
 
 #### Exercises
diff --git a/13_Day_Controlled_Versus_Uncontrolled_Input/13_uncontrolled_input.md b/13_Day_Controlled_Versus_Uncontrolled_Input/13_uncontrolled_input.md
index f9149db..3286ef3 100644
--- a/13_Day_Controlled_Versus_Uncontrolled_Input/13_uncontrolled_input.md
+++ b/13_Day_Controlled_Versus_Uncontrolled_Input/13_uncontrolled_input.md
@@ -14,7 +14,7 @@
 
 </div>
 
-[<< Day 12](../12_Day_Forms/12_forms.md) | [Day 14 >>]()
+[<< Day 12](../12_Day_Forms/12_forms.md) | [Day 14 >>](../14_Day_Component_Life_Cycles/14_component_life_cycles.md)
 
 ![30 Days of React banner](../images/30_days_of_react_banner_day_13.jpg)
 
@@ -174,4 +174,4 @@ Most of the time we use controlled input instead of uncontrolled input. In case
 
 🎉 CONGRATULATIONS ! 🎉
 
-[<< Day 12](../12_Day_Forms/12_forms.md) | [Day 14 >>]()
+[<< Day 12](../12_Day_Forms/12_forms.md) | [Day 14 >>](../14_Day_Component_Life_Cycles/14_component_life_cycles.md)
diff --git a/14_Day_Component_Life_Cycles/14_component_life_cycles.md b/14_Day_Component_Life_Cycles/14_component_life_cycles.md
index fb00594..b16bedc 100644
--- a/14_Day_Component_Life_Cycles/14_component_life_cycles.md
+++ b/14_Day_Component_Life_Cycles/14_component_life_cycles.md
@@ -427,7 +427,7 @@ class App extends Component {
 
   shouldComponentUpdate(nexProps, nextState) {
     console.log(nextProps, nextState)
-    // if the return is true, the application will never update.
+    // if the return is true, the application will update.
     return true
   }
 
@@ -458,6 +458,7 @@ class App extends Component {
     this.state = {
       firstName: 'John',
       day: 1,
+      congratulate: '',
     }
   }
 
diff --git a/15_Third_Party_Packages/15_third_party_packages.md b/15_Third_Party_Packages/15_third_party_packages.md
index 991f5fb..5e626fe 100644
--- a/15_Third_Party_Packages/15_third_party_packages.md
+++ b/15_Third_Party_Packages/15_third_party_packages.md
@@ -448,4 +448,4 @@ Try to also learn how to use the package _classnames_ and _validator_.
 
 🎉 CONGRATULATIONS ! 🎉
 
-[<< Day 14](../14_Day_Component_Life_Cycles/14_component_life_cycles.md) | [Day 16 >>]()
+[<< Day 14](../14_Day_Component_Life_Cycles/14_component_life_cycles.md) | [Day 16 >>](../16_Higher_Order_Component/16_higher_order_component.md)