diff --git a/src/index.ts b/src/index.ts
index 1facbe5..a0380c5 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1 +1,3 @@
-console.log('heeee');
+
+
+export { default as sample } from "./sample"
diff --git a/src/sample.ts b/src/sample.ts
new file mode 100644
index 0000000..5b81933
--- /dev/null
+++ b/src/sample.ts
@@ -0,0 +1,11 @@
+const power = (n? : number) : number | undefined => {
+    if( typeof n === "undefined" || n === null){
+        return  undefined
+    }
+    if(typeof n !== "number"){
+        return undefined
+    }
+    return Math.pow(n, 2)
+}
+
+export default power
diff --git a/test/sample.test.js b/test/sample.test.js
new file mode 100644
index 0000000..a3404dd
--- /dev/null
+++ b/test/sample.test.js
@@ -0,0 +1,25 @@
+import {sample} from "../src"
+
+// Describe : top level to describe a block of test below is for what
+describe("Test Sample Function", () => {
+    // Test : is run for each test
+    test("Test N is Undefined", () => {
+        expect(sample(undefined)).toBe(undefined) // expect sample(undefined) return undefined
+    })
+
+    test("Test N is Null", () => {
+        expect(sample(null)).toBe(undefined)
+    })
+
+    test("Test N is not number",() => {
+        expect(sample("Hello")).toBe(undefined)
+    })
+
+    test("Test Normal Number",() => {
+        expect(sample(0)).toBe(0)
+        expect(sample(1)).toBe(1)
+        expect(sample(2)).toBe(4)
+        expect(sample(100)).toBe(10000)
+    })
+
+})