How to set ToString("00") for hours/minutes/seconds when changed on button click

I have a WPF App where I have a Timer, I did everything accept how to when the numbers of hours/minutes/seconds are changing on button click, they should stay in this format: 01, 02, 03 etc. and by me it’s 1, 2, 3 etc.

here is my code for hours Up and Down click:

private void btnHoursPlus_Click(object sender, RoutedEventArgs e)
        {

            int number = Convert.ToInt32(tbHours.Text);
            if (number < 24)
            {
                tbHours.Text = $"{number + 1}";
            }
        }

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private void btnHoursMinus_Click(object sender, RoutedEventArgs e)
        {
            int number = Convert.ToInt32(tbHours.Text);
            if (number > 0)
            {
                tbHours.Text = $"{number - 1}";
            }
        }

>Solution :

You can specify the number of digits when converting to a string.

tbHours.Text = $"{number - 1:D2}";
// result 01, 02, 03 ...

More information can be found in the Decimal entry on the link.