# Reverse Polish Notation

This is the HP-35 Calculator from 1972. Look at the cost! Great keyboard, and used Reverse Polish notation logic for entry, which seemed so logical.

*2*

HP 80, RPN, reverse polish notation, better system if you think about it. 5 hit enter, 2, then operation +, and answer 7 is displayed

*1*

HP 48GX by Hewlett Packard. I picked this up at a local flea market for 25$. It goes on eBay for upwards of 100 bucks! I love the HP's reverse polish notation. If you haven't given an HP a try, do! Next up, HP 50 GX.

*2*

*1*

The HP-15C Calculator Scientific Calculator was an RPN (Reverse Polish Notation) calculator that was popular with engineers back in the '80s, and it was manufactured from 1981 through 1989. It was a programmable calculator that had built-in support for complex numbers, matrix math, numeric integration, and root solving. It's small size (5” x 3.15”) allowed it to be carried in a shirt pocket.

*3*