TI-84 Plus CE Documentation

🚀 Getting Started

Welcome! This guide will help you learn how to use the TI-84 Plus CE calculator — whether you're using the physical device or our free online emulator. Both work exactly the same way.

Turning it On

Press the ON key in the bottom-left corner. The calculator will show the home screen. You'll see a blinking cursor in the top-left. That means it's ready.

To turn it off, press 2nd then ON. In our online version, just close the tab.

The Display

The TI-84 Plus CE has a full-color screen. The top bar shows your current settings (like RADIAN or DEGREE mode). The main area is where you type and see your answers.

Using the Home Screen

The home screen is where you type calculations. Type any math expression and press ENTER to see the answer. Your last few answers are stored and shown above the current entry.

To clear everything on the screen, press CLEAR once (clears the line) or twice (clears the whole screen).

⌨️ The Keyboard

The TI-84 Plus CE keyboard looks confusing at first — lots of keys! But once you understand the color system, it becomes easy.

Color Key System

• White labels: The main function of a key (what it does when you press it normally).
• Blue labels (above the key): The secondary function. Press 2nd first, then the key.
• Green labels (above certain keys): Alpha characters (letters). Press ALPHA first, then the key.

Important Keys

• 2nd — Activates the blue function above the next key you press.
• ALPHA — Activates the green letter above the next key you press.
• ENTER — Executes your calculation or confirms a selection.
• CLEAR — Clears the current input or the full screen.
• DEL — Deletes the character to the left of the cursor.
• (-) — The negative sign (next to ENTER). Different from the minus key!
• MODE — Opens the settings menu to change RADIAN/DEGREE and other options.

➕ Basic Math

Arithmetic Operations

The four basic operations work just like you'd expect:

• Addition: +
• Subtraction: −
• Multiplication: ×
• Division: ÷

Type your expression and press ENTER. For example: 3 + 4 × 2 gives 11 (the calculator follows order of operations automatically).

Exponents and Roots

• To raise a number to a power: use the ^ key. Example: 2 ^ 8 = 256.
• Square root: press 2nd + x². Then type your number inside the parentheses.
• Cube root: press MATH, then choose option 4: ∛(

Using Parentheses

Always use parentheses to control the order of operations. For example, to solve (3 + 4) × 2, type: (3 + 4) × 2 → Result: 14. Without parentheses, 3 + 4 × 2 = 11.

The Answer Key (Ans)

Press 2nd + (-) to insert Ans — this represents the last answer. You can use it in your next calculation. For example, if your last answer was 100, typing Ans / 4 gives 25.

⚙️ Setting Modes

The Mode menu controls how your calculator behaves. Press MODE to open it.

Key Mode Settings

• RADIAN vs DEGREE: This affects trig functions (sin, cos, tan). Most algebra classes use DEGREE. Most calculus uses RADIAN.
• FLOAT vs 0-9: FLOAT shows as many digits as needed. Choose a number (like 2) to fix decimal places, e.g., showing 3.14 instead of 3.14159265...
• FUNCTION vs PARAMETRIC vs POLAR: Stick with FUNCTION for standard graphing. Change to POLAR for polar coordinates.
• REAL vs a+bi: Use a+bi when working with complex (imaginary) numbers.

📈 Graphing Basics

Graphing is one of the most powerful features of the TI-84 Plus CE. Here's how to graph any equation step by step.

Step 1: Enter Your Equation

Press Y= (top-left function key). You'll see slots labeled Y1, Y2, Y3, etc. Type your equation next to Y1. Use X,T,θ,n to enter the variable x.

Example: To graph y = 2x + 3, type 2X + 3 next to Y1.

Step 2: Set Your Window

Press ZOOM and choose 6: ZStandard for a standard -10 to 10 window. Or press WINDOW to set custom x and y min/max values.

Step 3: View the Graph

Press GRAPH. Your equation will be drawn on the screen.

Graphing a Circle

A circle like x² + y² = 25 has two parts. Solve for y first: y = ±√(25 − x²). Enter √(25 − X²) in Y1 and −√(25 − X²) in Y2. Then press ZOOM → 5: ZSquare so the circle looks like a circle (not an oval).

🔲 Window Settings

Press WINDOW to set up your viewing window. This controls what part of the coordinate plane you see.

• Xmin / Xmax: The left and right edges of the x-axis.
• Xscl: The spacing between x-axis tick marks.
• Ymin / Ymax: The bottom and top edges of the y-axis.
• Yscl: The spacing between y-axis tick marks.

Useful ZOOM Shortcuts

• ZOOM 1: Box Zoom — draw a box around the area you want to zoom into.
• ZOOM 3: Zoom In — zoom in centered at current cursor position.
• ZOOM 4: Zoom Out — zoom out from current position.
• ZOOM 6: ZStandard — reset to standard ±10 window.
• ZOOM 7: ZTrig — best window for trig functions (0 to 2π on x-axis).

🔍 Tracing & Tables

Using TRACE

After graphing, press TRACE. A small cursor appears on your graph. Use the left/right arrow keys to move along the curve. The x and y values display at the bottom of the screen.

If you have multiple graphs, press the up/down arrows to jump between them.

Finding Key Points

Press 2nd + CALC to open the Calculate menu:

• 1: value — Find y when you type an x value.
• 2: zero — Find x-intercepts (where the graph crosses the x-axis).
• 3: minimum — Find the lowest point of a curve.
• 4: maximum — Find the highest point of a curve.
• 5: intersect — Find where two graphs cross each other.
• 7: ∫f(x)dx — Approximate the area under a curve (integral).

The TABLE Feature

Press 2nd + GRAPH to open the table. It shows y values for a list of x values. This is great for creating data tables quickly.

Customize the table with 2nd + WINDOW (TBLSET). Set TblStart for the first x value and ΔTbl for the step size between x values.

📐 Algebra & Equations

Solving Equations by Graphing

The best way to solve an equation like x² − 3x − 4 = 0 is to graph Y1 = x² − 3x − 4 and find the x-intercepts using 2nd + CALC → 2: zero.

Solving Systems of Equations

To solve two equations simultaneously (like y = 2x + 1 and y = −x + 4):

1. Enter equation 1 in Y1 and equation 2 in Y2.
2. Press GRAPH.
3. Press 2nd + CALC → 5: intersect.
4. The calculator shows the solution (the x,y point where they cross).

Polynomial Operations

Use the MATH menu to access functions like:

• abs( — Absolute value. Example: abs(-7) = 7.
• round( — Round a number. Example: round(3.567, 2) = 3.57.
• iPart( / fPart( — Integer part or fractional part of a number.

📊 Statistics

Entering Data

Press STAT → 1: Edit to open the data list editor. Type your numbers into L1 (and L2 if you have two variables). Press ENTER after each number.

One-Variable Statistics (1-Var Stats)

After entering data in L1, press STAT → arrow right to CALC → 1: 1-Var Stats. Press ENTER twice. You'll see:

• x̄ — Mean (average)
• Σx — Sum of all values
• σx — Population standard deviation
• Sx — Sample standard deviation
• n — Number of data points
• Med — Median (scroll down to see)

Linear Regression

Enter your x values in L1 and y values in L2. Press STAT → CALC → 4: LinReg(ax+b). The calculator gives you the slope (a), y-intercept (b), and R² value (how well the line fits your data).

Histograms and Box Plots

Press 2nd + Y= (STAT PLOT). Turn Plot1 on and choose the type: histogram, box plot, or scatter plot. Then press ZOOM → 9: ZoomStat to auto-fit the window to your data.

🔢 Matrices

Creating a Matrix

Press 2nd + x⁻¹ (MATRIX). Arrow right to EDIT. Select [A]. Type the dimensions (rows × columns), then enter each value and press ENTER.

Matrix Operations

Back at the home screen, press 2nd + x⁻¹ to select a matrix. Then you can:

• Add matrices: [A] + [B]
• Multiply: [A] × [B]
• Find the inverse: [A]⁻¹ (press x⁻¹ after selecting [A])
• Find the determinant: Go to MATRIX → MATH → det(

Solving Systems with Matrices (RREF)

Enter your augmented matrix in [A], then go to MATRIX → MATH → B: rref(. Type rref([A]) and press ENTER. The result is the reduced row echelon form — your solution is in the last column.

📏 Trigonometry

Sin, Cos, Tan

The trig functions are on the third row of the keyboard: SIN, COS, TAN.

Make sure your MODE is set to DEGREE or RADIAN depending on your problem. A common mistake is using degrees when the calculator is in radian mode.

• sin(30°) = 0.5 (in DEGREE mode)
• sin(π/6) = 0.5 (in RADIAN mode)

Inverse Trig Functions

To find an angle from a ratio, use inverse trig:

• 2nd + SIN → sin⁻¹( — "What angle has this sine value?"
• 2nd + COS → cos⁻¹(
• 2nd + TAN → tan⁻¹(

Example: sin⁻¹(0.5) = 30° in DEGREE mode.

Graphing Trig Functions

Go to Y= and type your function. For y = sin(x), press ZOOM → 7: ZTrig. This sets the window perfectly for one full cycle of a sine wave (from −2π to 2π).

❌ Error Messages & Fixes

Error messages can be confusing. Here's what the most common ones mean and how to fix them:

ERR: SYNTAX

You made a typing mistake in your expression. Common causes: missing a parenthesis, using multiplication sign wrongly, or using the subtraction key instead of the negative sign.

ERR: DOMAIN

You're asking the calculator to do something mathematically undefined. Examples: log(−5), √(−4) (in REAL mode), or 1/0. Check your input.

ERR: WINDOW RANGE

Your window settings are invalid (e.g., Xmin is greater than Xmax). Press ZOOM → 6: ZStandard to reset.

ERR: DIM MISMATCH

You're trying to add or multiply matrices (or lists) that have different sizes. Make sure both matrices have compatible dimensions.

ERR: SINGULAR MAT

You tried to invert a matrix that has no inverse (its determinant is 0). Check your matrix values.

⚡ Shortcuts & Power Tips

Recall Previous Entries

Press the ↑ up arrow on the home screen to scroll through your recent calculations. Press ENTER to re-use or edit them. This saves tons of time!

Store Values in Variables

You can store a number into a letter variable. Type the number, press STO→, then press a letter (using ALPHA + key). Example: 42 STO→ A. Now every time you type A in an expression, the calculator uses 42.

Quick Fractions

Press MATH → 1: ►Frac to convert a decimal to a fraction. Example: type 0.375, then press ENTER, then MATH → ►Frac → ENTER. Result: 3/8.

Type π and e

π (pi): Press 2nd + ^. Use this in trig and geometry.

e (Euler's number): Press 2nd + LN for e^(, or 2nd + ÷ for the constant e itself.

Use Lists for Multiple Calculations

Type a list in curly braces: {1, 2, 3, 4, 5}. You can apply any operation to all values at once. For example, {1, 2, 3}² + 1 gives {2, 5, 10}. Incredibly useful for statistics and pattern problems!