diff --git a/.gitignore b/.gitignore
index 59f2945..fa5ff87 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,10 +3,10 @@
 .vscode
 
 # Lock File
-yarn.lock
+**/yarn.lock
 
 # Node Modules
-node_modules
+**/node_modules
 
 # Built
 dist
diff --git a/example/index.js b/example/index.js
new file mode 100644
index 0000000..21bf570
--- /dev/null
+++ b/example/index.js
@@ -0,0 +1,6 @@
+const { sample } = require("lib-name")
+
+console.log("Example : ")
+console.log("==========================")
+console.log("Result of 2 = ", sample(2))
+console.log("Result of 4 = ", sample(4))
diff --git a/example/package.json b/example/package.json
new file mode 100644
index 0000000..e97f181
--- /dev/null
+++ b/example/package.json
@@ -0,0 +1,14 @@
+{
+  "name": "lib-example",
+  "version": "1.0.0",
+  "description": "Example of Develop Library",
+  "main": "index.js",
+  "license": "MIT",
+  "private": false,
+  "dependencies": {
+    "lib-name": "link:../"
+  },
+  "scripts": {
+    "start": "node index.js"
+  }
+}
diff --git a/package.json b/package.json
index 1940924..14bb476 100644
--- a/package.json
+++ b/package.json
@@ -10,7 +10,8 @@
   "scripts": {
     "build": "tsc",
     "test": "jest",
-    "build:test": "yarn jest && yarn build"
+    "build:test": "yarn jest && yarn build",
+    "run:example": "cd example && yarn start"
   },
   "devDependencies": {
     "@babel/core": "^7.11.4",
diff --git a/src/index.ts b/src/index.ts
index a0380c5..8d6b961 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,5 @@
 
 
-export { default as sample } from "./sample"
+export { default as power } from "./sample"
+
+export { default as sqrt } from "./sample2"
diff --git a/src/sample2.ts b/src/sample2.ts
new file mode 100644
index 0000000..78a079a
--- /dev/null
+++ b/src/sample2.ts
@@ -0,0 +1,11 @@
+const sqrt = (n : number): number | undefined => {
+    if( typeof n === "undefined" || n === null){
+        return  undefined
+    }
+    if(typeof n !== "number"){
+        return undefined
+    }
+    return Math.sqrt(n)
+}
+
+export default sqrt
diff --git a/test/sample.test.js b/test/sample.test.js
index a3404dd..3bfb36a 100644
--- a/test/sample.test.js
+++ b/test/sample.test.js
@@ -1,25 +1,25 @@
-import {sample} from "../src"
+import {power} 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
+        expect(power(undefined)).toBe(undefined) // expect sample(undefined) return undefined
     })
 
     test("Test N is Null", () => {
-        expect(sample(null)).toBe(undefined)
+        expect(power(null)).toBe(undefined)
     })
 
     test("Test N is not number",() => {
-        expect(sample("Hello")).toBe(undefined)
+        expect(power("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)
+        expect(power(0)).toBe(0)
+        expect(power(1)).toBe(1)
+        expect(power(2)).toBe(4)
+        expect(power(100)).toBe(10000)
     })
 
 })
diff --git a/test/sample2.test.js b/test/sample2.test.js
new file mode 100644
index 0000000..d3c65a2
--- /dev/null
+++ b/test/sample2.test.js
@@ -0,0 +1,25 @@
+import {sqrt} from "../src"
+
+// Describe : top level to describe a block of test below is for what
+describe("Test Sample 2 Function", () => {
+    // Test : is run for each test
+    test("Test N is Undefined", () => {
+        expect(sqrt(undefined)).toBe(undefined) // expect sample(undefined) return undefined
+    })
+
+    test("Test N is Null", () => {
+        expect(sqrt(null)).toBe(undefined)
+    })
+
+    test("Test N is not number",() => {
+        expect(sqrt("Hello")).toBe(undefined)
+    })
+
+    test("Test Normal Number",() => {
+        expect(sqrt(0)).toBe(0)
+        expect(sqrt(1)).toBe(1)
+        expect(sqrt(4)).toBe(2)
+        expect(sqrt(10000)).toBe(100)
+    })
+
+})