<input type="text" ng-model="vm.price" name="price" placeholder="請輸入成交單價" required/><input type="text" ng-model="vm.number" name="number" placeholder="請輸入成交數量" required/><input type="text" ng-model="vm.amount" name="amount" placeholder="請輸入成交價格" required/>vm.amount = vm.price * vm.number 怎么保留兩位小數?希望得到大家的幫助,謝謝!