That's awesome. Great job.
My only minor comment is maybe increasing the size of the text.
The minus (-) sign and (.)deciman point kinda looks very similar, and they're also side by side.
You can make the 0 digit (2) blocks wide, and put the decimal point (.) to where the  key currently resides. From a usability point of view, I think the decimal point should be grouped with the digits....
But those are just minor comments. Great job again.