Click "Type". Type a number, press enter, then either +, -, *, or /, then press enter, and enter another number, and then press enter. There are two easter eggs.
Note added 22 February 2016, Credit to Brook10M7 (title changed as of 26 February 2016) December 5, 2017: Added another easter egg, after this project has not been changed since March 10, 2016.
