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Recalculate one formula for different values with CALC

Enter a formula once, then change its variable to obtain several results.

4 steps

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Suppose you need the areas of two circles with radii and . Instead of typing the calculation twice, enter the formula once and change the radius using CALC:

The calculator will ask for the variable ; do not type or the equals sign into the calculation line.

Calculate both areas

Below each step is the screen you should see after pressing.

Next to each step is the screen you should see after pressing.

  1. Step 1

    In the ordinary calculation mode, enter . Use for the radius; do not substitute or yet.
    Press:

  2. Step 2

    Open CALC. On the 991CW-style keypad, press TOOLS and select CALC; on other keypads, press the CALC key. The formula stays above a prompt for .
    Press:
    Screen after step 2

  3. Step 3

    Enter and press the equals key. The result is ; the display also gives approximately .
    Press:
    Screen after step 3

  4. Step 4

    Press the equals key again to return to . Enter to replace the previous value and press the equals key; the new result is , approximately .
    Press:
    Screen after step 4

Check the results

For , , so ; for , , so . The unit comes from the problem: the calculator displays numbers, not an automatically attached unit. If you need a whole sequence of consecutive values as rows, the function-table task is a better fit than CALC.

The fx-991EX screen showing S = πa² with CALC prompting for a, mid-recalculation.

Recalculate a formula fast on your fx-991EX calculator

Enter S = πa² once, then use CALC to get areas for radius 3 and 5 without retyping — no download required.

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