diff --git a/session_3/index.html b/session_3/index.html
index 1fc0f23..b81c6d6 100644
--- a/session_3/index.html
+++ b/session_3/index.html
@@ -32,7 +32,7 @@ <h2>Gasoline price</h2>
         <label for="money">Money</label>
         <input type="number" id="money" />
       </div>
-      <button onclick="calcGasoline()">Calculate</button>
+      <button id="calc">Calculate</button>
     </form>
 
     <p id="answer"></p>
diff --git a/session_3/main.js b/session_3/main.js
index 9dbd211..fd19942 100644
--- a/session_3/main.js
+++ b/session_3/main.js
@@ -1,3 +1,5 @@
+const calcButton = document.querySelector('#calc');
+
 const calcGasoline = (e) => {
   e.preventDefault();
   const price = Number(document.getElementById('price').value);
@@ -18,6 +20,8 @@ const calcGasoline = (e) => {
   document.querySelector('#answer').textContent = 'something';
 };
 
+calcButton.addEventListener('click', calcGasoline);
+
 const tempConventer = (id, value) => {
   const val = parseFloat(value);