Perform Calculations in Cabri Jr. on the TI84 Plus
Cabri Jr. for the TI84 Plus graphing calculator is capable of adding, subtracting, multiplying, and dividing any two measurements appearing on the screen. It can also find the square root of a measurement appearing on the screen.
To perform such calculations, follow these steps:

Press [GRAPH] to select the Appearance menu. Use the
keys to place the cursor on the Calculate option and press [ENTER] to select that option.
A symbol of the Calculate tool appears in the upperleft corner of the screen.

Press the key for the arithmetic operation you want to perform.
This is illustrated in the second picture, where the
key was pressed.

Use the arrow keys to move the cursor to the first measurement in the arithmetic expression and press [ENTER] to select that measure.
If you are adding, subtracting, multiplying, or dividing, select the second measurement in the arithmetic expression in the same way.
The measurement blinks when the cursor is placed on it. If you are calculating a square root, the calculation appears on the screen after you select the first measurement. For other operations, the calculation appears after the second measurement is selected.
To square a measurement, press [x] and then select that measurement two times.
All calculations are rounded to one decimal place.

Use the arrow keys to move the calculation to a better location and press [ENTER] to anchor that location.
This is illustrated in the third picture, where the calculation is placed after the word SLOPE.

Repeat Steps 2 through 4 to perform more calculations. When you are finished performing calculations, press [CLEAR] or select another menu item.