Every time there’s an IOS update, I have a few apps that have been abandoned by developers and won’t work with the new OS. Most I wouldn’t care about or could easily replace — but not GoCalc. I’m always relieved when it still works, because I use it nearly every day. Still awesome. I started simple, adding cooking conversions I use a lot. Then I added a few design conversions. But it turned into a mission-critical app when I created a set of formulas for all my estimating and billing. I'm not good at math, but by using the built-in apps as examples, and a little trial and error, I got them all working. Saves HOURS on these time-consuming tasks! Love being able to email the results to save with the paperwork. Would give it 5 stars if you had the option to clear all variables at once, and if you could duplicate an entire calculation to use as a base for a new one.