Cool app, but not easy to understand – Ivy big number calculator Review

I am glad that this app can work with big numbers. But it's not easy to learn. There is a help file that is complicated for a typical iOS app. I wish it provides some easy to understand examples and presentations. So, here are my problems: I don't know how to show numbers as comma separated digits; how to convert fractions to decimals; how to increase the precision of decimal places; and where are some useful functions (such as square root, power, and factorial).
Review by Samanz on Ivy big number calculator.