Casio fx-991CW: Editing Variables
Introduction
The newer set of Casio scientific calculators, better known as the Classwiz series, revised the way variables are dealt with. For the fx-991CW, storing and editing are dealt with through the Variable button, [ ⇄x ]. We have two options for recalling values of variables, one by the aforementioned variable button or by pressing [ SHIFT ] and the key that holds the variable that is needed.
In the Variables screen, use the key arrows to select a variable then press either [ OK ] or [ EXE ]. Depending on the calculator’s state and mode, we are given one of three options: Store, Edit, and/or Recall.
While editing variables, we are not restricted to just entering numbers. We can enter expressions that can be evaluated. This give us the ability to store several values in one screen.
Apps on the fx-991CW: Ability to Edit Variables in the Variable Screen
App |
Access |
Notes |
Calculate |
Yes |
|
Statistics |
Yes |
|
Distribution |
Yes |
|
Spreadsheet |
Yes |
|
Table |
Yes |
|
Equation |
Yes |
|
Inequality |
Yes |
|
Complex |
Yes |
Catalog-Complex menu is limited to i, ∠ |
Base |
No |
|
Matrix |
Yes |
|
Vector |
Yes |
|
Ratio |
Yes |
|
Math Box |
Only during input and Relative Freq (frequency) results screens |
|
Notes:
* In the Variable Edit screen, the Catalog-Func Analysis menu contains only the functions logab, log, and ln.
* The [ ↓FORMAT↑ ] button is inactive in the Variable Edit screen.
* The [ f(x) ] (FUNCTION) button is inactive in the Variable Edit screen.
* Expressions can include other variables including its own.
* Executing the expression by pressing the [ EXE ] also stores the result to the variable.
Examples
Example 1: Use the Variable Edit screen to store the following:
A = 2^2, B = 2^4, and C = 2^3
Keystrokes:
[ ⇄x ] (variable key) select A, select Edit, 2 [ x² ] [ OK ]**
Select B, select Edit, 2 [☐^☐] 3 [ OK ]
Select C, select Edit, 2 [☐^☐] 4 [ OK ]
Result:
A = 4, B = 8, C = 16
Example 2: Use the Variable Edit screen to store the following:
E = 11/5, F = 11/(5 + E), x = 11 * F/E
Keystrokes:
[ ⇄x ], select E, select Edit, 11 [ ÷ ] 5 [ OK ]
Select F, select Edit, 11 [ ÷ ] [ ( ] 5 [ + ] [ SHIFT ] (E) [ ) ] [ OK ]
Select x, select Edit, 11 [ × ] [ SHIFT ] ( F ) [ ÷ ] [ SHIFT ] (E) [ OK ]
Result:
E = 2.2, F = 1.527777777, x = 7.638888888
** or [ EXE ]
Side note: it’s fun to find and use Unicode symbols, like ⇄ (21C4) and ☐ (2610).
Eddie
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