angular 2 how to sum column ngFor

Question

trying to understand how to sum the column from table, every is added with *ngFor ( like todo-list), i wanna sum one of column, how i can do it in angular 2 ? So i have table

Answer 1

getSum(): number {
    let sum = 0;
    for (let i = 0; i < this.items.length; i++) {
      sum += this.items[i].num1;
    }
    return sum;
  }