diff --git a/src/sort-numbers/example-built-in-sort/sort-numbers.js b/src/sort-numbers/example-built-in-sort/sort-numbers.js
index c5b7571..bfda4c1 100644
--- a/src/sort-numbers/example-built-in-sort/sort-numbers.js
+++ b/src/sort-numbers/example-built-in-sort/sort-numbers.js
@@ -16,15 +16,6 @@
  * sortNumbers([-1, 0, 1]);
  * // -> [-1, 0, 1]
  */
-export const sortNumbers = (arrOfNumbers = []) => {
-  // create a copy of the argument to avoid side-effects
-  const copiedAndSorted = [...arrOfNumbers];
+export const sortNumbers = (arrOfNumbers = []) =>
+  [...arrOfNumbers].sort((a, b) => a - b);
 
-  // sort the copy according to
-  copiedAndSorted.sort((a, b) => {
-    return a - b;
-  });
-
-  // return the copied & sorted array of numbers
-  return copiedAndSorted;
-};
diff --git a/src/sort-numbers/example-built-in-sort/sort-numbers.spec.js b/src/sort-numbers/example-built-in-sort/sort-numbers.spec.js
index 1ee26a5..18ec90f 100644
--- a/src/sort-numbers/example-built-in-sort/sort-numbers.spec.js
+++ b/src/sort-numbers/example-built-in-sort/sort-numbers.spec.js
@@ -65,4 +65,15 @@ describe('sortNumbers sorts an array of numbers', () => {
       expect(arg).toEqual([3, 2, 1]);
     });
   });
+  describe('edge cases', () => {
+    it('returns empty array when input is empty', () => {
+      const received = sortNumbers([]);
+      expect(received).toEqual([]);
+    });
+  
+    it('returns same array when it has one number', () => {
+      const received = sortNumbers([42]);
+      expect(received).toEqual([42]);
+    });
+  });
 });