I would say (as a General Navigation instructor) that the degrees, minutes and seconds button is one of the most helpful functions in answering exam questions quickly without errors. I would also add that an "ANS" button (to input the last answer at any chosen point in a calculation) is very handy and for Radio Nav an "ENG" button is useful (this expresses the number as a multiple of the most convenient power of ten, in steps of 3, e.g. it would turn 112 370 000 into 112.37x10^6. Useful for working out whether you are seeing hundreds of MHz or GHz) and an "EXP" button to input in a similar fashion.
A 1/x button (or x^-1) is also handy if you know how to use it to take the reciprocal of a number.
All scientific calculators have the trigonometric functions, and most nowadays have all the extra functions mentioned. There is a Sharp one (with a white case) which often lasts about 6 months before the front falls off. It is still useable, but irritating if you are just taking your exams. Most of my students use a Casio fx-83MS available from Tesco for around £7-8
Last edited by Send Clowns; 25th July 2003 at 17:54.