I have a quilters Fabricalc also, and it works great with a small learning curve.
However, I find myself more and more using instead a free Android App from Robert Kaufman fabrics, that I installed on my android smartphone. It doesn't do everything that the dedicated calculator does, but does most of the commonly used functions.
The app is free from the android store and is called QuiltCalc. I don't know if there's a Ipad version of it, but I wouldn't doubt that there is.