Only increment for one time...

Question

Hi!

 

I have this code then its works well. But I need to increment only once. Means that when I click on the button its should "add" or increment ONLY once time. Then when you click again to increment a number. Its can accept. How can I do it please?

 

 

decimal d1, d2, total;

decimal.TryParse(lblResFactN.Text, out d1);

decimal.TryParse("1", out d2);

total = d1 + d2;

lblTotal.Text = total.ToString();