The entire object is made up of cubes. I'm confident the dimensions are mostly to scale. I UVed all the buttons(except the + button) together, so I only had to UV three objects total.I actually hadn't thought how to texture it before I started. I came up with the quick solution of just throwing something together with MS PowerPoint and Paint, took about 2-3 minutes. Imported that image into Mudbox and textured the model with it.
The final poly count came out to exactly 250. If I were modeling it for a game, I would have used a hi-poly and normal map to get the buttons. That would bring the poly count down to only 10, the amount the calculator body is made of.

