title: How to Sum up the values of 5 diff columns as TOTAL using *ngONinit?
body: <p>i am having an array of Product with fields name ID,Brand,Price,QtySold,Value where value=Price*qtySold and at the end i need to show Number of Items,Total quantity sold and total sales value</p>
  
  <pre><code> @Component
  ({
   selector: 'my-app',
   templateUrl: './app.component.html',
   styleUrls: [ './app.component.css' ]
   }`
  export class AppComponent{
  allProduct:Product[]=[
  {Id:'P104', Brand:'Pepsi',Price:4,qtySold:22},
  {Id:'C124', Brand:'Coke',Price:4,qtySold:26},
  {Id:'M155', Brand:'Maggie',Price:6,qtySold:10},
  {Id:'DM241', Brand:'Cadburys',Price:10,qtySold:15},
  {Id:'5S118', Brand:'5 Star',Price:8,qtySold:8},
  ];
  </code></pre>
  
  <p>Need to display the Number of Products,Sum of Quantity sold and sum of Sales Value</p>