The Question Mark - blog by Mark Volkmann

TI-84 Calculator

Powering on and off

Press on to turn it on and 2nd on to turn it off. It will turn off automatically after 3 to 4 minutes of inactivity.

Operating system

To get information about the operation system of your calculator:

  • press 2nd mem
  • select About
  • I have version CE OS 5.4.0.0034

Display brightness

To change the display brightness, press 2nd up arrow and 2nd down arrow

Home screen

To return to the home screen from any other screen, press 2nd quit.

Date and time

To set the date and time, press mode and select “SET CLOCK”.

The date and time are only displayed here on the mode screen.

Many button presses display a menu of options.

Select a menu item by pressing the number in front of it or move to a menu item with the up and down arrows and press enter.

There are five shortcut menus labeled f1 through f5 on the top row, all accessed with the alpha key.

  • f1 provides items to enter a fraction (n/d), enter a mixed fraction (Un/d), convert between these (>n/d<>Un/d), and convert between fraction and decimal (>F<>D) (apparently nobody knows what the U stands for)
  • f2 provides abs, summation, nDeriv, fnInt, logBASE, x root, nPr, nCr, and !
  • f3 provides a way to enter a matrix up to 6x6
  • f4 provides a way to use a y= equation
  • f5 doesn’t seem to work

Entering exponents

  • enter an expression (can be just a number or letter)
  • press ^ key
  • enter exponent expression (can be just a number)
  • press right arrow to return to previous level

Editing expressions

Use the left and right arrows to position the cursor and hold down to repeat.

Press del to delete the character under the cursor. There seems to be no backspace key.

Press any number, letter, or operator key to replace the character under the cursor.

Press 2nd ins to switch to insert mode instead of replace mode and press any arrow key to return to replace mode.

Variables

To store a number in a variable, enter the number, press sto->, enter a variable letter, and press enter.

To use a variable in an expression, enter its letter name or press 2nd rcl followed by its letter name to see the value.

To merely see the value in a variable, enter its letter name and press enter.

Converting between decimal numbers and fractions

To convert a decimal number to a fraction:

  • enter the decimal number
  • press math
  • select Frac
  • press enter

History

To recall a previous line from history so it can be optionally edited and re-executed:

  • press up and down arrows
  • press enter to copy the expression as the current expression
  • optionally edit it
  • press enter again to execute it

To delete an expression from history:

  • press up and down arrows to locate the expression
  • press clear

To delete all expressions in history, press 2nd catalog (0 key) and select CLEAR ENTRIES.

Characters

To enter a character, press alpha and then the character key To enter several letters without needing to press alpha before each, press 2nd A-lock. To unlock, press alpha.

There are 27 supported letters, A-Z and theta.

The “X,Y,theta,n” key inserts one of these four characters depending on the mode:

  • X for Function mode
  • T in Parametric mode
  • theta in Polar mode
  • n in Seq mode

Fractions

To enter a fraction:

  • press alpha link (not labeled) to display a fraction with placeholders for numerator and denominator (alternately, press alpha f1 and select n/d or U n/d)
  • enter a numerator expression
  • press left or down arrow
  • enter a denominator expression

Logarithms

For a natural log (base e), press ln and enter a number.

For a log with base 10, press log and enter a number.

For a log with some other base, such as log base a of b:

  • press log when enters “log(”
  • enter the value for b
  • press comma key
  • enter the value for a
  • if more terms need to be entered, press ) and enter the terms
  • press enter

Cursor

To move the cursor the beginning of the expression, press 2nd left arrow (unlabeled). To move the cursor the end of the expression, press 2nd right arrow (unlabeled).

To clear the current expression, press clear. To clear all expressions, press clear a second time. The previous expressions are still present, just not visible. Press the up arrow to revisit expressions.

Degrees vs. Radians

To switch between degree and radian modes:

  • press mode
  • highlight RADIAN or DEGREE
  • press enter

To convert degrees to radians:

  • if not already in RADIAN mode, switch to that
  • enter value in degrees
  • press 2nd angle
  • highlight the degree symbol and press enter
  • press enter again

To convert radians to degrees:

  • if not already in DEGREE mode, switch to that
  • enter value in radians
  • press 2nd angle
  • highlight the r symbol and press enter
  • press enter again

To convert a radian value to a fraction of pi:

  • divide by pi by pressing the division key, pi, and enter
  • press math
  • highlight Frac and press enter
  • press enter again

To convert radians to degrees:

Imaginary numbers

To work with imaginary numbers:

  • press mode
  • if “real” is selected, select “a+bi” instead

Function graphs

To graph one or more functions:

  • press y= to enter the functions, optionally specify the color and line/fill type of each here by pressing left arrow to move to color/line icon
  • press graph to graph the functions
  • press window to adjust the Xmin, Xmax, Xscl, Ymin, Ymax, and Yscl values
  • press trace to see the y value of a function at a given x value
    • press left or right change the x value whose y value is being displayed
    • a marker for the point will appear in the graph
    • press up or down to move the cursor to a different function

To disable a function from being graphed without deleting it:

  • press y=
  • use the up and down arrows to move to the function
  • use the left and right arrows to move to the =
  • press enter to toggle the function off (white background) or on (black background)

To evaluate a function at a specific x value:

  • with the graph displayed, press 2nd calc
  • select value
  • enter an x value
  • if more than one function is graphed, press the up and down arrows to change the function whose y value is displayed
  • no y value will be displayed if there is a discontinuity at the x value

To graph all equations simultaneously instead of in sequence, press mode and select SIMUL.

To find minimum values, maximum values, or y intercepts

  • press 2nd calc
  • select minimum, maximum, or zero (for y intercepts)
  • press left or right to move the cursor just to the left of the expected value
  • press enter
  • press left or right to move the cursor just to the right of the expected value
  • press enter
  • press enter again to guess the value using a numerical analysis technique
  • repeat for other values

To zoom in or out on a graph

  • press zoom
  • select a zoom option
    • ZStandard resets to standard zoom which is Xmin=Ymin=-10 and Xmax=Ymax=10
    • both “Zoom In” and “Zoom Out” wait for you to select a center point. Use the arrow keys to move to the center point and press enter.
  • press enter

Scatter plots

To create a scatter plot:

  • press stat and select Edit…
  • enter all the x values in the L1 list
  • press the right arrow
  • enter all the y values in the L2 list
  • press 2nd “stat plot”
  • if there are previous plots, select PlotsOff and press enter to clear them
  • press 2nd “stat plot”
  • select the plot to use: Plot1, Plot2, or Plot3
  • if it is currently Off, select On
  • select the plot Type: scatter, line, bar, ?, ?, or step
  • select the lists containing the data to plot in Xlist and Ylist by pressing 2nd and L1 to L6 (often want L1 and L2)
  • select the Mark to use for each point
  • select the Color
  • press graph
  • press zoom and select ZoomStat to zoom so all the points are visible
  • press trace and use the left and right arrows to see the coordinates of each point

Linear regression

To add a line of best fit to a scatter plot:

  • press stat
  • press right arrow to select CALC
  • select LinReg
  • Xlist should be L1
  • Ylist should be L2
  • move to “Store RegEQ”
  • press vars
  • press right arrow to move to Y-VARS
  • select Function
  • select an available function variable to hold the linear regression equation that will be calculated
  • select Calculate
  • the equation will now be saved in the y= list
  • it will also display values for a and b in the line equation y=ax+b
  • press graph

Histograms

To create a histogram (a.k.a. bar chart):

  • draws a bar for each unique value whose height indicates the number of times that value appears in the list
  • enter values in a single list just like for a scatter plot
  • press 2nd “stat plot”
  • select Plot1
  • turn it On
  • select Type histogram icon
  • set Xlist to the list to be plotted by pressing 2nd and one of L1 to L6
  • press zoom
  • select ZoomStat
  • press graph
  • press window to adjust the x and y scales; Xmin is the lowest value; Xmax is the highest value; Xscl controls the width of each bar Ymin is the lowest count of a value (typically zero); Ymax is the highest count of a value
  • to see the value of each bar, press trace and the left and right arrows to move between the bars; the value is between min= and max<; the frequency is the n= value; set Xscl to 1 to make min= be the value

Matrices

To enter/edit a named matrix:

  • press 2nd matrix
  • press right arrow twice to highlight EDIT
  • press up and down arrows to highlight a matrix name (A-J)
  • press enter
  • if the desired number of rows is not already selected, enter the number of rows and press right arrow or enter
  • if the desired number of columns is not already selected, enter the number of columns and press enter
  • enter an expression in each cell, pressing enter after each
  • press 2nd quit to return to home screen

To recall a named matrix:

  • press 2nd matrix,
  • press up and down arrows to highlight a matrix name
  • press enter

To enter an unnamed matrix:

  • press alpha f3
  • if MTRX is not selected, press left and right arrows to select it
  • if the desired number of rows is not already selected, press the up arrow to move the cursor off of OK, press the up and down arrows to select a number of rows, and press right arrow or enter
  • if the desired number of columns is not already selected, press the up and down arrows to select a number of columns, and press enter
  • press down arrow repeatedly to move to OK and press enter
  • enter an expression in each cell pressing right arrow after each
  • to store the unnamed matrix in a named matrix, press sto-> 2nd matrix, press up and down arrows to select a matrix name, and press enter

To delete a named matrix:

  • press 2nd mem
  • select “Mem Management/Delete…”
  • select “Matrix…”
  • press up and down arrows to highlight a matrix name
  • press del

To multiply compatible matrices:

  • press 2nd matrix (NAMES will be highlighted)
  • press up and down arrows to highlight a matrix name
  • press enter to select it
  • repeat the steps above to select another matrix
  • press enter to multiply them

To calculate the inverse of a matrix:

  • press 2nd matrix (NAMES will be highlighted)
  • press up and down arrows to highlight a matrix name
  • press enter to select it
  • press “x^-1” key (under math key)

To calculate the determinant of a matrix:

  • press 2nd matrix
  • press right arrow to highlight MATH
  • select “det(”
  • press 2nd matrix
  • press up and down arrows to highlight a matrix name
  • press enter to select it
  • optionally press )
  • press enter

To calculate the adjugate of a matrix:

  • This seems to not be supported

To copy a matrix:

  • press 2nd matrix
  • press up and down arrows to highlight a matrix name
  • press enter to select it
  • press sto->
  • press 2nd matrix
  • press up and down arrows to highlight a matrix name
  • press enter to select it
  • press enter

Custom programs

To upload a program to the calculator:

  • install the “TI Connect CE” app on a computer
  • launch the app
  • download calculator apps to your computer
  • unzip them to get .8xp files
  • connect the calculator to the computer using the USB cable
  • click the Explorer icon in the left nav of the “TI Connect CE” app
  • drag .8xp files from the computer to the right side of the “TI Connect CE” window

To run a program on the calculator:

  • press 2nd catalog
  • select Asm( and press enter
  • press prgm
  • select the app and press enter
  • press enter again to start the app
  • press clear to exit the app

To archive a program:

  • press 2nd mem
  • select Archive,
  • press prgm
  • select a program
  • press enter
  • archived programs have a * in front of their name

PineappleCAS

  • This is a “computer algebra system” (CAS) for TI-84 Plus CE calculators.
  • See here
  • To install it, follow the instructions at the link above. Note that both the file PCAS.8xp and the file clibs.8xg must be installed.
  • If you get “ERROR: MEMORY” when running PCAS, try archiving every program you have installed and running again.
  • each operation runs on a given y= equation and writes the result to another y= equation specified at the top of the UI
  • select a function in the left column
  • select options in the right column
  • select the button at the bottom of the right column
  • wait for the calculation to complete
  • select Close
  • exit the program by pressing clear
  • press y= to view the result
  • Simplify combines like terms.
  • Evaluate evaluates constant expressions to simplify an equation.
  • Expand expands multiplication. For example, (x - 2)(x + 3) expands to x^2 + x - 6
  • Derivative finds the derivative of an equation; example: derivative of 3x^2 - 2x + 4 is 6x - 2

Program creation

To create a program:

  • press prgm
  • select NEW
  • press enter
  • enter a name, up to 8 characters
  • enter commands
  • to enter ”, press alpha +
  • to toggle between insert and overstrike modes, press 2nd ins

Typing lowercase letters

Note: This may not work in newer versions of the TI-84 operating system because use of Assembly programs is disabled.

To enable typing lowercase letters:

  • backup the calculator first in case this goes wrong
  • press prgm
  • select NEW
  • enter LOWRCASE for the name
  • press 2nd catalog to access list of commands
  • select AsmPrgm or Asm84CEPrgm (This is disabled by default in the os 5.3.1 to prevent cheating so students can’t write Assembly programs on their calculators. To enable it, connect to a computer.)
  • enter the assembly program FDCB24DEC9 with no space after AsmPrgm
  • press 2nd quit
  • press 2nd catalog
  • select Asm(
  • select LOWRCASE
  • press enter
  • press alpha once for uppercase letters and twice for lowercase