Why doesn't await wait for the previous await to complete?

Question

.NET

There are 3 methods:
1. Reading from a file:

public Task LoadFromFileAsync()
        {
            return Task.Run(() =>
            {
                //загрузка данных из файла
            });
        }

2. Calculations. simultaneously launches 3 methods of various kinds of calculations:

public async Task StartCalculationAsync()
        {
            Task.Factory.StartNew(() => Calculation1());
            Task.Factory.StartNew(() => Calculation2());
            Task.Factory.StartNew(() => Calculation3());
        }

3. Saving results:

public Task SaveToFileAsync()
        {
            return Task.Run(() =>
            {
                SaveToFile();
            });
        }

In the event handler, they are called like this:

private async void button_Click(object sender, RoutedEventArgs e)
        {
            await LoadFromFileAsync(); //выполняется 10-15 секунд
            await StartCalculationAsync(); //может выполняться часами
            await SaveToFileAsync(); //выполняется 1-2 секунды
        }

LoadFromFileAsync is executed, StartCalculationAsync waits for LoadFromFileAsync to complete and then starts executing. But at the same time, SaveToFileAsync starts running. Why is this happening? After all, SaveToFileAsync must wait for StartCalculationAsync to complete.
And why the moderator removed the "Programming" tag. Is this not programming?

Answer 1

Here

public async Task StartCalculationAsync()
{
            Task.Factory.StartNew(() => Calculation1());
            Task.Factory.StartNew(() => Calculation2());
            Task.Factory.StartNew(() => Calculation3());
}

you startanuli 3 threads, but you do not return the created Task objects. What should the program wait for?
Task.WaitAllhelp you