Before you download make sure to have Redpower 2 Pr6 Installed as well as Minecraft forge
Links:
- www.eloraam.com/download-redpower/
- www.minecraftforge.net/forum/index.php?topic=4175.0
Includes:
Handy Number pad
Multiplier
Adder
Subtracter with a built-in negative number thingy
Decimal Display
(Recommended: computer that is not ancient)
(for best use of world: use magic launcher)
To do list:
What to do list!

Additional Notes

Update as of 2-15-14: I realize that the display decoders could have been half the size they are now that I've looked into it. The new design I've come up with uses 100% cells (null, inverted, and non-inverted) and does binary to seven segment with almost 0 wires.