Example of how to use Number in Typescript (#20802)

* Example of how to use Number in Typescript

* updated with changes suggested in review

* updated indent in code block

* updated based on @itaisteinherz suggestions

guide/english/typescript/number-type/index.md

@@ -12,4 +12,22 @@ let decimal: number = 7;
 let hex: number = 0xf00d;
 let binary: number = 0b0110;
 let octal: number = 0o531;
-```
+```
+
+Example of Number type usage in TypeScript:
+
+```typescript
+class Employee extends Person {
+  age: Number;
+  constructor(age: Number){
+    // Calls constructor of Person
+    super();
+    this.age = age;
+  }
+ 
+  getAge(): Number {
+    return this.age;
+  }
+}
+
+```