custom code? We are producing a simple measuring instrument that will have an embedded handheld calculator. We may mass produce these items if the prototype is successful. Does anyone know if we can program a basic hand calculator somehow?

- the calculator needs to be inexpensive (few dollars) and is NOT a sophisticated programmable calculator
- it will need a few lines of custom code (including math function Tangent and pi)
-it needs to be quite small (approx 2"x2") and thin (aprox 3/16" thick)
- it needs to accept user input, calculate (with the few lines of code), then respond with the result.

Example:
User is prompted, then inputs A
User is prompted, then inputs B
User is prompted, then inputs C

Calculator respond with Answer D

So, if anyone knows were we can purchase inexpensive, simple, wholesale calculators that can be custom programmed for a single purpose, it would be appreciated.

Thanks.