[Vuejs]-Vue Computed how to set

In your case, you should use methods instead of computed properties.

methods: {
  displayNumbers(Numbers) {
      return Numbers
  }
}

Or maybe filters.

filters: {
  displayNumbers(Numbers) {
    return Numbers
  }
}

and in your template:

<span class="eachnumber" >{{ savedlottoNumber.numbers | displayNumbers }}</span>