I want to sum the column of a table in angular but it does not work: for example if I want to sum the `2000` and `3000` and `4000` it gives me `200030004000`, but I want to sum it means `9000`, it is concatenation.

**client.component.ts** 

```js
clients: Client[];
total: number=0;

constructor(private clientService:ClientService) { }

ngOnInit() {
    this.clientService.getClients().subscribe(clients => {
        this.clients=clients;
        this.total = this.getTotal();
    });
}

getTotal() {
    return this.clients.reduce((total, client) => {
        return total + client.balance;
    }, 0)
}

```

**client.component.html**

```html
<div class="col-md-6">
    <h4 class="text-right">Total : {{ total | currency:"USD": "symbol" }}</h4>
</div>

```