private void btnCalc_Click(object sender, EventArgs e)
        {
           // Take in Data from text box and convert to integer
            int numCopies = Convert.ToInt32(txtCopies.Text);

           // Create two temp variables for math we need to do
            double tempCost;
            double tempCopies;

            if (numCopies <= 100)
            {
           //Calculate the cost if number of copies is less than 100
               tempCost = numCopies * 0.1;

           //Output to text box and multiple by 23% to add vat
                txtIncVat.Text = Convert.ToString(tempCost * 1.23);
            }
            else if (numCopies <= 200)
            {
           //If its greater than 200 we know the first 100 will be charged at 10 cent we need to find how many will be at 6 cent. We must take the 100 from the number of copies to find the number left over. The left over is how many will be charged at 6 cent
                tempCopies = numCopies - 100;

           // We add the first 100 at 10 cent and then we take the remaining copies and charge them at 6 cent.
               tempCost = (100 * 0.1) + tempCopies * 0.06;

          // Output the cost to the text box
                txtIncVat.Text = Convert.ToString(tempCost * 1.23);
            }
            else
            {
         // This time we take 200 because we know the first 100 at 10 cent and the second 100 at 6 cent we need the final remainder.
                tempCopies = numCopies - 200;

        //Then finally add the cost of the first 100 at 10 cent, the second 100 at 6 cent, then we get our remainder and multiply it by 4 cent.
                tempCost = (100 * 0.1) + (100 * 0.06) + tempCopies * 0.04;
                txtIncVat.Text = Convert.ToString(tempCost * 1.23);

            }
        }