Value 1 here has an amount of 10000, then I got the result in Value2 total of 8500, in Value3 I will input an a desired amount then Add it to the Value2.Ex: 1000 8500. So what happened to me is I cant add Value3 Value2 = Value4. I hope someone could help me.

https://stackblitz.com/edit/sum-ef7c94?file=src/app/app.component.ts,src/app/app.component.html

.html

<input style="width:300px" type="number"  (keypress)="numberOnlyWithDecimal($event,xyz)" 
[readonly]="true" [(ngModel)]="value1">

<input style="width:300px" type="number"  (keypress)="numberOnlyWithDecimal($event,xyz)" 
[readonly]="true" [(ngModel)]="value2" value = "{{myMath.abs(value1 * 0.15 - value1)}}">

<input style="width:300px" type="number"  (keypress)="numberOnlyWithDecimal($event,xyz)" 
[readonly]="true" [(ngModel)]="value3" >

<input style="width:300px" type="number"  (keypress)="numberOnlyWithDecimal($event,xyz)" 
[readonly]="true" [(ngModel)]="value4" value = "{{myMath.abs(value3   value2)}}">

CodePudding user response：

import { Component } from '@angular/core';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  value1: number = 10000;
  value2: number = Math.abs(this.value1 * 0.15 - this.value1);
  value3: number = 0;
  value4: number = Math.abs(this.value2   this.value3);

  public myMath = Math;

  ngOnInit() {}
}

<div >
  <div >
    <input
      type="number"
      
      placeholder="FirstNumber"
      [(ngModel)]="value1"
    /><br />

    Total<input
      value="{{ myMath.abs(value1 * 0.15 - value1) }}"
      type="number"
      
      placeholder="Total"
      [(ngModel)]="value2"
    /><br />

    <input
      type="number"
      
      placeholder="Input an Amount"
      [(ngModel)]="value3"
    />

    <input
      type="number"
      
      placeholder=""
      [(ngModel)]="value4"
      value="{{ myMath.abs(value2   value3) }}"
    />
  </div>
</div>

Now you know how to add the 8500 to the Input amount ex: 1000   8500

Or check this snippet:

https://stackblitz.com/edit/sum-sqe2kv?file=src/app/app.component.ts,src/app/app.component.html,src/app/app.component.css