I'm using ngrx store to record state, my state currently holds my list of accounts and the current page (for paging).

On my list of accounts component i call the store to get the current page and pass that to a service (web api) to get the list of accounts.

```
this.currentPage$ = this.store.select(getCurrentPage);

```

My angular service is expecting a variable (currentPage) but as a type of number, the store select returns an Observable.

```
getListOfCustomer(currentPage: number): Observable<ListDto<CustomerList>> {}

```

My variable `this.currentPage$` is currently a type of `Observable<number>`

How can i convert an 
`Observable<number>` to a `number` to pass it to my service?