ExamCalc - a simple Java-language Android-based app for timing examinations. It will tell you when a given exam ends, and factor in time for breaks taken and any extra time allocated, totally removing the need for mental arithmetic of hours and minutes etc.
This is the open source project upon which all future versions of ExamCalc will be based. Pull requests and contributors welcome!
To build, the recommended environment is Android Studio. I hope this app helps invigilators to time more efficiently, have fun!