diff --git a/challenges/calculadora/src/components/Calculator.jsx b/challenges/calculadora/src/components/Calculator.jsx
index a32dd73..ee567ce 100644
--- a/challenges/calculadora/src/components/Calculator.jsx
+++ b/challenges/calculadora/src/components/Calculator.jsx
@@ -22,19 +22,126 @@ export default class Calculator extends Component {
         this.clearMemory = this.clearMemory.bind(this)
         this.setOperation = this.setOperation.bind(this)
         this.addDigit = this.addDigit.bind(this)
+        this.calculate = this.calculate.bind(this)
     }
 
     //Seu objetivo é implementar estas funções
+
+    calculate(){
+		/*
+			this method will calculate the result and show it on the display
+		*/
+		let result = 0
+        switch(this.state.operation){
+			case '+':
+				result = this.state.values[0] + this.state.values[1]
+				break;
+			case '-':
+				result = this.state.values[0] - this.state.values[1]
+				break;
+			case '*':
+				result = this.state.values[0] * this.state.values[1]
+				break;
+			case '/':
+				result = this.state.values[0] / this.state.values[1]
+				break;
+			default: break;
+		}
+		const resultString = result.toString()
+
+		/*
+			it verifies if the number have more than 9 digits. If true, it verifies if the number has 10 digits and is
+			a negative number. If true, the method simply displays the number with the minus sign before it
+		*/
+		if(resultString.length > 9){
+			if(resultString.length === 10 && result < 0){
+				this.setState({
+					...this.state,
+					displayValue: resultString,
+					clearDisplay: true,
+				})
+			}
+			else{
+				this.setState({
+					...this.state,
+					displayValue: 'Erro',
+				})
+			}
+		}
+		else{
+			this.setState({
+				...this.state,
+				displayValue: resultString,
+				clearDisplay: true,
+			})
+		}
+	}
+
+
     clearMemory() {
-        // ERrrRRooOrRR: 8932183!
+		/*
+			this method will reset the state to the initial state, clearing the memory
+		*/
+        this.setState({
+            ...initialState,
+        })
     }
 
-    setOperation(operation) {
-        // ERrrRRooOrRR: 2162621 ;-;!
+    async setOperation(operation) {
+        if(operation === '='){
+            /*
+                if the operation is '=', the method will await the setState and then call the calculate method
+            */
+		    await this.setState({
+				...this.state,
+				values: [this.state.values[0], parseFloat(this.state.displayValue)]
+			})
+            this.calculate()
+        }
+        else{
+            /*
+				if the operation is not '=', the method will set the operation in state to the operation called
+            */
+            this.setState({
+                ...this.state,
+                operation: operation,
+                clearDisplay: true,
+            })
+        }
     }
 
     addDigit(n) {
-        // ErrrroR: 7163271 ;-;
+		/*
+			it will verify if the display value has less than 9 digits. If the number has more than 9 digits,
+			it does nothing for aesthetic purposes, cause more than 9 digits on the display causes the exceeding 
+			digits to disappear from the display, making difficult to see the real number that is on the state
+		*/
+		if(this.state.displayValue.length === 9 && !this.state.clearDisplay);
+
+        // it will verify if it is the first number of the operation or not
+        else if(!this.state.clearDisplay){
+            /* 
+                if it is the first number of the operation, the method will verify if there is only a 0 in the display;
+                if true, it will replace the zero with the digit clicked;
+                if false, it will put the number in front of the last added digit;
+            */
+            this.setState({
+                ...this.state,
+                displayValue: this.state.displayValue === '0' ? n.toString() : this.state.displayValue + n.toString(),
+            })
+        }
+        else{
+            /*
+                if there was a number already added to the operation, the method will replace the entire number in the display
+                for the digit clicked
+            */
+            this.setState({
+                ...this.state,
+                clearDisplay: false,
+                values: [parseFloat(this.state.displayValue), 0],
+                displayValue: n,
+            })
+        }
     }
 
     render() {
diff --git a/challenges/calculadora/src/components/Header.jsx b/challenges/calculadora/src/components/Header.jsx
index a9e2c88..6c32f39 100644
--- a/challenges/calculadora/src/components/Header.jsx
+++ b/challenges/calculadora/src/components/Header.jsx
@@ -5,7 +5,7 @@ export default function() {
     return <header>
                 <h1>Commit Pull Hackquest 2020</h1>
                 <h2>
-                    <img class="commit" src="https://www.commitjr.com/wp-content/uploads/2020/06/commit-jr_arara_512_512.png"/>
+                    <img class="commit" alt="Commit Jr logo" src="https://www.commitjr.com/wp-content/uploads/2020/06/commit-jr_arara_512_512.png"/>
                 </h2>
             </header>;
 }
\ No newline at end of file
diff --git a/challenges/calculadora/src/index.js b/challenges/calculadora/src/index.js
index d1fc7e7..975150a 100644
--- a/challenges/calculadora/src/index.js
+++ b/challenges/calculadora/src/index.js
@@ -1,4 +1,4 @@
-import React, { Fragment } from 'react';
+import React from 'react';
 import ReactDom from 'react-dom';
 
 import './index.css';