<div id="app">
  <div><input type="text" v-model.number="num1"> + <input type="text" v-model.number="num2"> = {{ sum }}</div>
</div>
var vm = new Vue({
  el: "#app",
  data: {
    num1: 0,
    num2: 0
  },
  computed: {
    sum() {
      return this.num1 + this.num2;
    }
  }
});

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/vue/2.6.11/vue.min.js