private void btnBacktoMenu_Click(object sender, EventArgs e)
{
this.Close();
NPage1 np1 = new NPage1();
np1.Show();
}
private void button1_Click(object sender, EventArgs e)
{
NPage1 n1 = new NPage1();
n1.Show();
this.Hide();
MessageBox.Show("Click on a number to start learning \nClick next to move to the next set of numbers");
}