diff --git a/algorithm-exercises-csharp-test/src/hackerrank/warmup/SimpleArraySum.Test.cs b/algorithm-exercises-csharp-test/src/hackerrank/warmup/SimpleArraySum.Test.cs
new file mode 100644
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+++ b/algorithm-exercises-csharp-test/src/hackerrank/warmup/SimpleArraySum.Test.cs
@@ -0,0 +1,31 @@
+namespace algorithm_exercises_csharp;
+
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+[TestClass]
+public class SimpleArraySumTest
+{
+  public class SimpleArraySumTestCase
+  {
+    public int[] inputs = [];
+    public int expected = 0;
+  }
+
+  // dotnet_style_readonly_field = true
+  private static readonly SimpleArraySumTestCase[] tests = [
+    new() { inputs = [1, 2, 3, 4, 10, 11], expected = 31 }
+  ];
+
+  [TestMethod]
+  public void testSimpleArraySum()
+  {
+    int? result;
+
+    foreach (SimpleArraySumTestCase test in tests)
+    {
+      result = SimpleArraySum.simpleArraySum(test.inputs);
+      Assert.AreEqual(test.expected, result);
+    }
+  }
+}
+
diff --git a/algorithm-exercises-csharp/src/hackerrank/warmup/SimpleArraySum.cs b/algorithm-exercises-csharp/src/hackerrank/warmup/SimpleArraySum.cs
new file mode 100644
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+++ b/algorithm-exercises-csharp/src/hackerrank/warmup/SimpleArraySum.cs
@@ -0,0 +1,23 @@
+// @link Problem definition [[docs/hackerrank/warmup/simple_array_sum.md]]
+
+namespace algorithm_exercises_csharp;
+
+using System.Diagnostics.CodeAnalysis;
+
+public class SimpleArraySum
+{
+  [ExcludeFromCodeCoverage]
+  protected SimpleArraySum() { }
+
+  public static int simpleArraySum(int[] inputs)
+  {
+    var total = 0;
+
+    foreach (int i in inputs)
+    {
+      total += i;
+    }
+
+    return total;
+  }
+}
diff --git a/docs/hackerrank/warmup/simple_array_sum.md b/docs/hackerrank/warmup/simple_array_sum.md
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+++ b/docs/hackerrank/warmup/simple_array_sum.md
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+# [Simple Array Sum](https://www.hackerrank.com/challenges/simple-array-sum/problem)
+
+Difficulty: #easy
+Category: #warmup
+
+Given an array of integers, find the sum of its elements.
+For example, if the array $ ar = [1, 2, 3], 1 + 2 + 3 = 6 $, so return $ 6 $.
+
+## Function Description
+
+Complete the simpleArraySum function in the editor below. It must return the sum
+ of the array elements as an integer.
+simpleArraySum has the following parameter(s):
+
+- ar: an array of integers
+
+## Input Format
+
+The first line contains an integer, , denoting the size of the array.
+The second line contains  space-separated integers representing the array's elements.
+
+## Constraints
+
+$ 0 < n, ar[i] \leq 1000 $
+
+## Output Format
+
+Print the sum of the array's elements as a single integer.
+
+## Sample Input
+
+```text
+6
+1 2 3 4 10 11
+```
+
+## Sample Output
+
+```text
+31
+```
+
+## Explanation
+
+We print the sum of the array's elements: $ 1 + 2 + 3 + 4 + 10 + 11 = 31 $.