SgtGodswordBerserker has implemented a multi-function scientific calculator using Minecraft, a project that echoes the earlier projects to build a CPU and a 3D printer using the game engine and its primitives.
Specs: 6 digit addition and subtraction, 3 digit multiplication, division and trigonometric/scientific functions. (The reason these are only 3 digits is because multiplication and division would take a long time to decode/complete/encode. Also, the fraction display is hard enough to build for 3 digits, let alone 6 - 6 digit RAM would not only be massive, but a bit pointless since the curves follow the same pattern surrounding the peaks.). Graphing y=mx+c functions, quadratic functions, and equation solving of the form mx+c=0.
The screen and keypad were always meant to be the main feature of this machine. The main display boasts 25 digits. Square root signs are displayed and can change to accommodate any number of digits. Square root signs, add, minus, multiply and divide signs are displayed at appropriate times, and there is a full fraction display. The 7-segments for the fractions are the smallest possible, being only 3 wide, and stackable vertically and horizontally.
...The calculator itself is just over 250x200x100 blocks. It contains 2 6-digit BCD number selectors, 2 BCD-to-binary decoders, 3 binary-to-BCD decoders, 6 BCD adders and subtractors, a 20 bit (output) multiplier, 10 bit divider, a memory bank and additional circuitry for the graphing function.
Minecraft Scientific/Graphing calculator - Sin Cos Tan Log Square root (Thanks, Fipi Lele!)