feat: solve No.2413

Author: BaffinLee

Diff for: 2401-2500/2413. Smallest Even Multiple.md

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+# 2413. Smallest Even Multiple
+
+- Difficulty: Easy.
+- Related Topics: Math, Number Theory.
+- Similar Questions: Greatest Common Divisor of Strings, Three Divisors, Find Greatest Common Divisor of Array, Convert the Temperature, Minimum Cuts to Divide a Circle.
+
+## Problem
+
+Given a **positive** integer ```n```, return **the smallest positive integer that is a multiple of **both** **```2```** and **```n```.
+ 
+Example 1:
+
+```
+Input: n = 5
+Output: 10
+Explanation: The smallest multiple of both 5 and 2 is 10.
+```
+
+Example 2:
+
+```
+Input: n = 6
+Output: 6
+Explanation: The smallest multiple of both 6 and 2 is 6. Note that a number is a multiple of itself.
+```
+
+ 
+**Constraints:**
+
+
+	
+- ```1 <= n <= 150```
+
+
+
+## Solution
+
+```javascript
+/**
+ * @param {number} n
+ * @return {number}
+ */
+var smallestEvenMultiple = function(n) {
+    return n % 2 === 0 ? n : n * 2;
+};
+```
+
+**Explain:**
+
+nope.
+
+**Complexity:**
+
+* Time complexity : O(n).
+* Space complexity : O(n).