Is there a way to handle all the number buttons in one keyboard event instead of doing for each buttons in a calculator?

Instead of copying and pasting for each number is there a method that could reference to all buttons?

private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            if(e.KeyCode == Keys.D5)
            {
                Five.PerformClick(); 
                    
            }
        }

        private void Form1_KeyUp(object sender, KeyEventArgs e)
        {
            if(e.KeyCode == Keys.D5)
            {
                Five.PerformClick();
            }
        }

>Solution :

Firstly, the enum values Keys.D0 to Keys.D9 have sequential integer values. You can abuse this knowledge to turn the KeyCode directly into an array index.

var buttons = new Button[] {Zero, One, ... etc ...};
if(e.KeyCode >= Keys.D0 && e.KeyCode <= Keys.D9){
    var index = (int)e.KeyCode - (int)Keys.D0;
    var button = buttons[index];
    button.PerformClick();
}
if(e.KeyCode >= Keys.NumPad0 && e.KeyCode <= Keys.NumPad9){
    // similar to the above
}

Or you could rearrange your code. Create a separate method for doing the work of "user entered a digit". Then call that method from both the button click event and form key event.

private void HandleDigit(int value){
    // todo
}

private void Form1_KeyDown(object sender, KeyEventArgs e)
{
    if(e.KeyCode >= Keys.D0 && e.KeyCode <= Keys.D9){
        var value = (int)e.KeyCode - (int)Keys.D0;
        HandleDigit(value);
    }
}