[Attention Surplus Disorder]

I bought a mint HP12C at a garage sale for $5, with pouch & manual and was actually working in mortgage finance when I did. I kind of wish I had the motivation and attention span to learn how to use it.

[Conan the Librarian]

I have an 11C that I bough in 1985. Still works quite well.

[alternatives?]

I found it easier to just do the Algebra. Most stated interest rates are nominal on a monthly basis as opposed to annual effective rates.