I built a working calculator in Minecraft. It works with command blocks (no redstone curcuits) and structure blocks for displaying and installing. The result is not shown on the display but on the sidebar.
I made this to play around with the /scoreboard command and the structure blocks. The idea came to me when I saw the /scoreboard players operation... command on the wiki.

How 2 install:

You can just download the world from the link or install it in any 1.10 world following these steps:

1. You have to use 1.10.x or later.
   
2. Unpack the downloaded .zip file.
   
3. Move the structure folder in the save folder of your map or paste all the structures in your existing structures folder.
   
4. Give yourself a structure block using the command: /give @p structure_block .
   
5. Load the structure "installer" using your structure block.
   
6. Now you can see where the structure will be loaded.
   
7. Pull the lever and everything will be installed.
   
8. You might want to turn the command block feedbacks off using the command: /gamerule commandBlockOutput false
   
   
9. Now you can explore my creation :)
   

You can change where the controls will be by editing the top right structure block of the installer (named controls). To do that just change the value of the relative Z-position. It's at 32 by default which is already the maximum size so you can only get the controls closer to the diplay. If you want to place only a display simply remove this structure block.

You can have multiple displays and controlling devices. Every display will show the same. I did not use relative or absolute coordinates between the controls and the display, The device just triggers armor stands at the display. So you can put the segments where ever you want but the display must be facing south.
The file is not a .schematic so Schemagic doesn't work.

The resourcepack I am using is Sphax PureBDcraft 64x 1.10R1 + 3D Blocks and Technology Add-on

If you have any suggestions, questions, wishes, opinions or even found a bug fell free to leave a comment!

Hope you like my little creation!
If so, please leave a diamond. thx!