This is by far the best calculator I have used and seen out there! The functions that this one has blows away the Construction Master Pro. I’m amazed at all the functions that this app can do. Spring and Compound angle for Crown molding!!! Awesome! I’m a finished carpenter and I really love this app. The Help menus are my favortie part! It’s hard enough to remember how to use all the functions and formulas. The Help menus really are nicely done will illustrations and easy to follow “how to”. Thank you for this app. Spend the $20, it’s so worth it!!