My 2 cents
Im glad I'm done and will never have to do this bad boy again!
My down fall was practicing with a different calculator than the one they supply.
The logic was different and the buttons in different locations, hence my muscle memory was out.
My tip is to pay the $20 for the same one they supply.....it takes the pain out of redoing calclation after calculation after pressing the wrong button or pressing the Sqrt button in the wrong sequence!!
Enjoy