Busicom 10 digit Mini Pocket Scientific Calculator School Business Office FM-15

I bought this with low expectations - but this thing does 99.99% of what any student/engineer needs from a calculator - there are others that do much more (i've got quite a few rom casio, TI etc) - but for most day to today stuff in science/engineering, this is exactly what's needed - it's nice and small, has protective cover and the buttons are really nice and responsive. The display is clear. It's a 10 digit unit, it has a working register, hexadecimal mode (no logic operations, but does conversions to 32 bit between hex, octal, binary in twos comp to +511/-512). Calc forensics (invsin(invcos(invtan(tan(cos(sin(9)))))) = 8.99999986001, which is very good. Get one - or get 9 - get only -8.99999986...