problem3 and problem 4 added

index.html

@@ -16,20 +16,20 @@ <h5>What is Problem Eueler?</h5>
 			<p>Project Euler is a website with a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. The motivation for starting Project Euler, and its continuation, is to provide a platform for the inquiring mind to delve into unfamiliar areas and learn new concepts in a fun and recreational context.</p>
 			<p>You can visit and join here: <a href="https://projecteuler.net/">https://projecteuler.net</a></p>
 		</div>
-		<!-- First Problem -->
+		<!-- Problem 1 -->
 		<div class="problemContainer">
 			<h2>Problem 1</h2>
 			<h4>Multiples of 3 and 5</h4>
 			<br />
-			<p>If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23. Find the sum of all the multiples of 3 or 5 below given number.</p>
+			<p>If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.<br /><br />Find the sum of all the multiples of 3 or 5 below given number.</p>
 			<br />
 			<input id="input1" type="number" min="1" max="10000" placeholder="Enter your number" />
 			<button id="btn1">Calculate</button>
 			<br /><br />
 			<h5 class="answer">Answer: <span id="answer1"></span></h5>
 		</div>
 
-		<!-- Second Problem -->
+		<!-- Problem 2 -->
 		<div class="problemContainer">
 			<h2>Problem 2</h2>
 			<h4>Even Fibonacci numbers</h4>
@@ -41,7 +41,32 @@ <h4>Even Fibonacci numbers</h4>
 			<br /><br />
 			<h5 class="answer">Answer: <span id="answer2"></span></h5>
 		</div>
+
+		<!-- Problem 3 -->
+		<div class="problemContainer">
+			<h2>Problem 3</h2>
+			<h4>Largest prime factor</h4>
+			<br />
+			<p>The prime factors of 13195 are 5, 7, 13 and 29.<br /><br />What is the largest prime factor of the given number?</p>
+			<br />
+			<input id="input3" type="number" min="1" max="5000000" placeholder="Enter your number" />
+			<button id="btn3">Calculate</button>
+			<br /><br />
+			<h5 class="answer">Answer: <span id="answer3"></span></h5>
+		</div>
 
+		<!-- Problem 4 -->
+		<div class="problemContainer">
+			<h2>Problem 4</h2>
+			<h4>Largest palindrome product</h4>
+			<br />
+			<p>A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.<br /><br />Find the largest palindrome made from the product of two same digit long numbers - specify the number of digits.</p>
+			<br />
+			<input id="input4" type="number" min="1" max="10" placeholder="Enter your number" />
+			<button id="btn4">Calculate</button>
+			<br /><br />
+			<h5 class="answer">Answer: <span id="answer4"></span></h5>
+		</div>
 	</div>
 
 

main.js

@@ -35,7 +35,6 @@ function problem2() {
 	var y = 1;
 	var sum;
 	var total = 0;
-	var array = [];
 	if (max === "") {
 		return "Uoh-ooh, you forgot to specify a number!";
 	}
@@ -45,7 +44,6 @@ function problem2() {
 	for (sum=0; sum<max; sum=x+y) {
 		if (sum%2 === 0) {
 			total += sum;
-			array.push(sum);
 		}
 		x=y;
 		y=sum;
@@ -54,3 +52,66 @@ function problem2() {
 }
 
 
+// PROBLEM 3: DOM
+var btn3 = document.getElementById("btn3");
+btn3.onclick = function() {
+	document.getElementById("answer3").innerHTML = problem3();
+};
+
+// PROBLEM 3: FUNCTION
+function problem3() {
+	var max = document.getElementById('input3').value;
+	if (max === "") {
+		return "Uoh-ooh, you forgot to specify a number!";
+	}
+	if(max > 5000000) {
+		return "Please specify a number between 0-5000000";
+	}
+	for (var i=2; i<=max; i++) {
+		if (!(max % i)) {
+			max /= i;
+			i--;
+		}
+	}
+	return i;
+}
+
+// PROBLEM 4: DOM
+var btn4 = document.getElementById("btn4");
+btn4.onclick = function() {
+	document.getElementById("answer4").innerHTML = problem4();
+};
+
+// PROBLEM 4: FUNCTION
+function problem4() {
+	var max = document.getElementById('input4').value;
+
+	// function to get the number range
+	var a = function(max) {
+		var digits = [];
+		for (var i = 0; i<max; i++) {
+			digits.push(9);
+		}
+		return [Number(digits.join('')), Number(digits.slice(0, -1).join(''))];
+	};
+	var b = a;
+
+	var palindromeArray = [];
+	if (max === "") {
+		return "Uoh-ooh, you forgot to specify both numbers!";
+	}
+	if(max > 10) {
+		return "Please specify numbers between 0-10";
+	}
+	for (var x=a[0]; x>a[1]; x--) {
+		for (var y = b[0]; y>b[1]; y--) {
+			var multiply = x * y;
+			var stringMultiply = multiply.toString();
+			var reversedMultiply = reverseString(stringMultiply);
+			if (reversedMultiply === stringMultiply) {
+				palindromeArray.push(multiply);
+			}
+		}
+	}
+	return Math.max.apply(null, palindromeArray);
+}

style.css

@@ -41,7 +41,9 @@ p {
 	text-align: center;
 	padding-top: 1.6em;
 	padding-bottom: 2em;
+	position: relative;
 }
+
 .title:after {
 	content: " ";
 	background-image: url(wavy-seperator.svg);