problem6 added

index.html

@@ -81,8 +81,20 @@ <h4>Smallest multiple</h4>
 			<h5 class="answer">Answer: <span id="answer5"></span></h5>
 		</div>
 
-
+		<!-- Problem 6 -->
+		<div class="problemContainer">
+			<h2>Problem 6</h2>
+			<h4>Sum square difference</h4>
+			<br />
+			<p>The sum of the squares of the first ten natural numbers is 385. The square of the sum of the first ten natural numbers is 3025. <br /><br /> Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 − 385 = 2640. <br /> <br /> Find the difference between the sum of the squares of the specified first natural numbers and the square of the sum.</p>
+			<br />
+			<input id="input6" type="number" min="1" max="200" placeholder="Enter your number" />
+			<button id="btn6">Calculate</button>
+			<br /><br />
+			<h5 class="answer">Answer: <span id="answer6"></span></h5>
+		</div>
 	</div>
+
 
 
 	<script src="main.js"></script>

main.js

@@ -172,4 +172,43 @@ function problem5() {
     return n * largestPower(2, max);
 }
 
+// PROBLEM 6: DOM
+var btn6 = document.getElementById("btn6");
+btn6.onclick = function() {
+	document.getElementById("answer6").innerHTML = problem6();
+};
+
+// PROBLEM 6: FUNCTION
+function problem6() {
+	var max = document.getElementById('input6').value;
+	if (max === "") {
+		return "Uoh-ooh, you forgot to specify a number!";
+	}
+	if(max > 200) {
+		return "Please specify a number between 0-200";
+	}
+
+	function squareSum(max) {
+		var i, s = 1,
+		e = Math.log(max) / Math.LN10;
+        // special case: max is a power of 10
+        if (e - (e << 0) === 0) {
+        	s = max * (max >> 1) + (max >> 1);
+        }
+        else {
+        	for (i = 2; i <= max; i += 1) {
+        		s += i;
+        	}
+        }
+        return s * s;
+    }
+    function sumSquare(max) {
+    	var i, s = 1;
+    	for (i = 2; i <= max; i += 1) {
+    		s += i * i;
+    	}
+    	return s;
+    }
 
+    return squareSum(max) - sumSquare(max);
+}