I used version 2.1.2 on an iPad running iOS 9.2.1. On the surface level, this is just an average calculator application. It has a very simple to use interface and a comfortably large array of mathematical commands, mostly the expected functions, but it also has some nice unusual parts, too, such as Euler’s Number, the standard acceleration of gravity, speed of light, etc. My favorite part, however, is the conversion table, offering conversions for many different types of data, including: currency, speed, mass, and even work. This is a very nice feature, considering there are some ludicrously complex conversion rates, such as those between a quart and a liter, with the conversion having over eight decimal places, so with the conversion table being a swipe over from the calculator side, it’s much easier to convert data between units. Another nice aspect of this application is that it supports Apple Watches, admittedly, I don’t have one, however, it’s nice to have that option. One downside is that it supposedly holds onto some conversions for those who pay a monthly membership fee, however, in my experience, I never ran into a conversion that was not available in the suite of the units available to free users. Overall, this app is a great tool for people not doing extremely complex math, and would probably work great alongside a high school Trigonometry or Algebra class.