Tactical calculator?

[Coltsp1]

Tactical calculator may sound goofy, but I have some perimeters that I want. Lightweight., waterproof, solar, and battery, lit screen and buttons on switch, on and off on switch or button I may be asking too much.

 

[Aftermath]

fx-260 SOLAR II Compact Scientific | Black Scientific Calculator | CASIO

The Black fx-260 SOLAR II compact scientific calculator features a 10-digit display that is large enough to handle decimals, fractions, exponentials, and statistics in addition to hundreds of other math functions.

www.casio.com

I think you'd still have to know the formula for the perimeter...