Calculator Button Ergonomics

Problem:
Calculator was traditionally a rectangular device, and when applied to a round interface on usual watches drastically reduce the tappable area for some of the buttons. Its very clear that you cant simply use square buttons on a round interface to get the same results.

Solution:
1. Buttons follow the curvature of the screen within which they are placed, dividing the available space equally.
2. The text within the button act as sort of a "target" to aim for, they are placed such a way that they dont necessarily form a grid, but identify the button's center.
3. For a right handed user (watch is worn on the left), this is a more ergonomic button semantic, given that the fingers will be pointing to the left of the screen.

Hope this changes things.