Numerical: Calculator Without Equal
Numerical started off as a pretend app made by Andrew J Clark at the end of 2013 as he learnt to develop iOS apps. Overtime the ambition of this first app grew and was eventually released in Feb 2014 as Numerical: Calculator Without Equal. It was featured on dozens of tech/design blogs, and went on to be downloaded 400,000 times. After a few delays Numerical² will be released shortly.
Find it on the App Store here.