A moderately old model of

scientific calculator made by

Casio in

Japan.
Mine is about 15 years old, and still works, mostly (more on that below). It's

solar powered so it never needs

batteries. It has several different modes, some of which can coexist with one another:

**SD**, a statistical mode that calculates standard deviations
**DECimal, BINary, OCTal, and HEXadecimal**, modes for doing calculations in other bases or converting between bases.
**DEGree, RADian, and GRAdient**, modes where the trigonometric functions work with different angle units.
**FIXed point, SCIentific, and NORMal**, modes that affect the number of digits displayed in the display. (I never use these, except of course that Normal is the default behavior.)

Functions available include

square,

square root,

cube root,

exponents and

nth root; base-10 and natural

logarithms, 10

^{x}, and e

^{x};

fraction and

degree-

minute-

second conversions;

sine,

cosine, and

tangent, and their

inverse and/or

hyperbolic versions; 18 levels of

parentheses;

permutations and

combinations;

reciprocal;

factorial;

rectangular to

polar coordinate conversions; a single

memory with the ability to store, retrieve, swap current value and memory, or add or subtract on the memory; and an extra

register which some of the functions that return two values (like the coordinate functions) stick values in.

Some functions are not available in some modes; for instance, the fraction, degree-minute-second, and trigonometric keys become digits A through F for HEX mode.

My calculator has a large crack in the back of the case behind the lower part of the keypad, but it still works. However, several years ago (long after it cracked) it decided it only wanted to be an 8-digit calculator instead of a 10-digit calculator like the case says. It's not that the first two digits on the display don't display anything; the calculator always displays the correct results, except that numbers of 10^{8} or more force it into scientific notation, and results with many decimal places are rounded to 8 digits in the display. The scientific notation display uses two extra digits to display the exponent up to ±99, and this much still works.