Any sufficiently advanced technology
is indistinguishable from magic.
[Arthur C. Clarke]
My first criteria for a good app is, it is simple. I’m a graphic designer and not a computer scientist. I look for apps that behave themselves (they work without bugs), and apps that are intuitive to use (they have a small learning curve). I spend my main self-education time keeping myself up to speed with my major software tools. I want my smaller apps to be more like a manual screwdriver than an electric drill with multiple bits. These two apps fit the criteria and are affordable.
MyScript© Calculator is magic for sure. It was free! How does Vision Objects© do that? Also it works well and is fun to use. Write numerals and function symbols (+, -, =, etc.) with a finger on a touchscreen and then watch your writing change into real equations with the correct answer. It even charmed my five-year old grandson. When I used it in a knitting class to help people figure their stitches and rows from their gauge, it was fast and accurate. Some students even downloaded the app for their smart phones during class.
Desktop Task Timer by Erik Asmussen is also a winner in my book. I track my design time for billing purposes. In the past 30 years, I have tried using a number of methods to accurately record time and translate it in to an invoice. This app ($0.99) is the best I’ve found so far. I’ve even started tracking my non-chargeable tasks just out of curiosity.