How to use Angular to Take User Input and Using It As JS Function Parameter

I need the user to be able to type in a number in the given input field and when they click on the submit button, it runs a javascript function that returns the factorial. How do I send the user’s input value to the javascript function? I found this online but it doesn’t seem to work: (P.S: I am using Angular)

export class FormComponent implements OnInit {
  findFactorial() {
    const number = document.querySelector(".number_field").value;
    console.log(number);
  }

  constructor() {}

  ngOnInit() {}
}
<form class="form">
  <mat-form-field class="full-width">
    <input
      matInput
      class="number_field"
      type="number"
      placeholder="Enter A Number"
      max="1000000000"
    />
  </mat-form-field>
</form>
<button class="btn" mat-raised-button color="primary" (click)="findFactorial()">
  Submit
</button>