Save value to a variable

Question

How can I save the value of a calculation done in front-end by passing to a variable in typescript, example:

Typescript:

valor:number=0;

html:

<ion-input type="number" [(ngModel)]="valor"></ion-input>
<p>{{valor * valor}}</p>

In typescript is stored only the value that was typed in the input, what needs is to put in a variable the calculation made by the paragraph: <p>{{valor * valor}}</p>

I tried the following logic without success:

Typescript:

this.result = this.valor * this.valor;

html:<p>{{result}}</p>