Trident Help

Natural Scientific 991 manual · Chapter 18 of 18

Reference

Resetting, number range and precision, display limits, and what this calculator does not include.

18.1Reset the calculator#

ChoiceWhat it does
SHIFTRESET9 then 1 (Setup Data)Restores SETUP to the defaults and keeps variables and history.
SHIFTRESET9 then 2 (Variable Memory)Sets A to F, x, y, M and Ans to zero.
SHIFTRESET9 then 3 (Initialize All)Everything: settings, variables, history, matrices, statistics data and the current app.

18.2Number range and precision#

  • Results are shown with up to 10 digits and calculated with more.
  • The largest number is about 9.999999999×10^99. Anything larger gives a Math ERROR; a result smaller than 10^-99 in size is rounded to 0 (underflow gives 0, not an error, as on handheld calculators of this kind).
  • Arithmetic is done in decimal, so 0.1 + 0.2 is exactly 0.3.
  • The calculator keeps your last 30 calculations in history.
  • Matrices go up to 4×4, vectors have 2 or 3 elements, simultaneous equations go up to 4 unknowns and polynomials up to degree 4.
  • A table can hold up to 45 rows.

18.3What is not included#

  • The Spreadsheet app (MENU 8) and the Inequality app (MENU B, the °'" key) are listed in the menu but show "Not available".
  • No graphing. For graphs use Natural Color Graphing or one of the other graphing models.
  • No unit conversions, scientific constants list or periodic table.
  • No verification, QR code or programming.
  • OFF (SHIFT AC) does nothing, because there is nothing to switch off.
  • No test of hypotheses or confidence intervals in Statistics; only one-variable results and regression.
  • The matrix and vector apps do not offer reduced row form or eigenvalues.

fx-991EX ClassWiz is a trademark of Casio Computer Co., Ltd.. Trident Calculator is an independent product by South View Studios and is not affiliated with, sponsored by or endorsed by Casio. The name is used only to describe the kind of calculator this model resembles; Trident's names, keys, display, fonts and software are its own clean-room design.