Sum Multiples
<p>Given a positive integer <code>n</code>, find the sum of all integers in the range <code>[1, n]</code> <strong>inclusive</strong> that are divisible by <code>3</code>, <code>5</code>, or <code>7</code>.</p>

<p>Return <em>an integer denoting the sum of all numbers in the given range satisfying&nbsp;the constraint.</em></p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> n = 7
<strong>Output:</strong> 21
<strong>Explanation:</strong> Numbers in the range <code>[1, 7]</code> that are divisible by <code>3</code>, <code>5,</code> or <code>7 </code>are <code>3, 5, 6, 7</code>. The sum of these numbers is <code>21</code>.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> n = 10
<strong>Output:</strong> 40
<strong>Explanation:</strong> Numbers in the range <code>[1, 10] that are</code> divisible by <code>3</code>, <code>5,</code> or <code>7</code> are <code>3, 5, 6, 7, 9, 10</code>. The sum of these numbers is 40.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> n = 9
<strong>Output:</strong> 30
<strong>Explanation:</strong> Numbers in the range <code>[1, 9]</code> that are divisible by <code>3</code>, <code>5</code>, or <code>7</code> are <code>3, 5, 6, 7, 9</code>. The sum of these numbers is <code>30</code>.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 10<sup>3</sup></code></li>
</ul>
Math
func sumOfMultiples(n int) (ans int) {
	for x := 1; x <= n; x++ {
		if x%3 == 0 || x%5 == 0 || x%7 == 0 {
			ans += x
		}
	}
	return
}