title: Angular forms validation on numbers
body: <p>I just did my first forms validation in Angular and it works really nice. Some of my input must be numbers only, and I would expect that to be fairly easy. However I only found some pretty complex extensions can this be true? Is there not an easy way to a simple validation for numbers?</p>
  
  <pre><code>this.registerForm = this.formBuilder.group({
     name: ['', Validators.required],
     type: ['', Validators.required],
     imo: ['', [Validators.required]],
     dwt: ['', Validators.required],
     built: ['', Validators.required],
     yard: ['', Validators.required],
     flag: ['', Validators.required]
   });
  </code></pre>