Getting Started With the Basics

The TI-84 Plus CE is a graphing calculator that works like a standard calculator for everyday math, but also graphs equations, stores data, and runs programs. When you first turn it on, you see the home screen — a blank area where you type problems and see answers. The ON button is in the bottom left. To turn it off, press 2ND (the blue key) and then ON.

The calculator uses a standard order of operations: it solves multiplication and division before addition and subtraction, just like paper math does. Type 3 + 4 × 2 and press ENTER, and you get 11, not 14. If you want 14, you type (3 + 4) × 2 instead. The parentheses keys are above the 8 and 9.

Every time you press ENTER, the calculator moves to a new line and shows your answer. You can scroll up and down through old problems using the arrow keys. This is useful if you want to check what you typed or use an old answer in a new problem.

Key Takeaways

  • The home screen is where you type math problems; press ENTER to solve and move to the next line.
  • Use 2ND plus a colored key to access the blue functions printed above each key.
  • The Y= key opens the graphing editor, where you enter equations to see their shape on the screen.
  • STAT lets you enter lists of numbers and create plots or run calculations on your data.
  • The MODE key controls how the calculator displays answers — degrees or radians, decimal or fraction format, and more.

Doing Fractions, Decimals, and Different Number Formats

By default, the TI-84 Plus CE shows answers as decimals. If you want fractions instead, press MODE, scroll down to the line that says "Float" or a number, and change it. Scroll right to "a/b" and press ENTER. Now when you divide 1 by 2, you see 1/2 instead of 0.5. To switch back to decimals, return to MODE and select "Float".

You can also convert a single answer from decimal to fraction without changing the mode. After you get a decimal answer, press 2ND and then PRB (above the 1 key). Scroll down to "Frac" and press ENTER. The decimal converts to a fraction on the spot.

If you are working with percentages, type the number, press 2ND, then % (above the 0 key). This divides by 100. So typing 25 and pressing 2ND % gives you 0.25. For 15% of 200, type 200 × 15 2ND % and press ENTER to get 30.

Graphing Equations and Reading the Graph

Press the Y= key at the top left to open the graphing editor. You see a list of equation slots: Y1, Y2, Y3, and so on. Type an equation using X as the variable. For example, type X^2 - 3 to graph a parabola. The ^ key is above the ÷ symbol. Press ENTER after each equation.

Once you have entered one or more equations, press GRAPH (top right) to see the picture. The calculator automatically picks a window that shows the important parts of the graph. If the graph looks wrong or you want to zoom in or out, press ZOOM (above TRACE). You see a menu with options like "ZoomIn", "ZoomOut", and "ZoomStandard". Select one and press ENTER.

To find where a graph crosses the x-axis or y-axis, press 2ND and then TRACE (which opens the CALC menu). Choose "Zero" to find where the graph touches the x-axis, or "Value" to see the y-value at any x-value you type. The calculator asks you to move the cursor near the spot you want, then it calculates the exact answer.

Working With Lists and Statistics

Press STAT to enter data mode. You see a table with columns labeled L1, L2, L3, and so on (L stands for "list"). Click on the first cell under L1 and type your numbers, pressing ENTER after each one. If you have two related sets of numbers — like test scores and study hours — put one set in L1 and the other in L2.

Once your data is entered, you can calculate the mean, median, and standard deviation. Press STAT, scroll right to "CALC", and choose "1-Var Stats" for one list or "2-Var Stats" for two lists. Press ENTER, then type the list name (like L1) and press ENTER again. The calculator shows you statistics for that data.

To draw a plot of your data, press 2ND and then Y= (which opens STAT PLOT). Choose Plot1, Plot2, or Plot3. Turn it on, pick a plot type like "scatter" or "histogram", and tell it which lists to use. Then press GRAPH to see your data as a picture. This helps you spot patterns or outliers at a glance.

Using Memory and Storing Values

If you calculate something you want to use again, you can store it. After you see the answer, press STO→ (the right arrow key above the 4), then type a letter like A, B, or X. Press ENTER. Now that letter holds that number. Type the letter in any future problem and the calculator uses the stored value.

You can also store equations or lists. In the Y= editor, you can save a graph by pressing 2ND and DRAW, then choosing "Store Picture". In the STAT editor, you can copy a list to another list by highlighting the list name, pressing 2ND and DEL, and choosing "Copy". This is useful if you want to keep a backup or work with the same data in different ways.

To see what you have stored, press 2ND and + (which opens MEM). You see options like "Mem Mgmt" that show you all your stored variables, lists, and programs. If you run out of space, you can delete old data here.

Changing Settings and Display Options

Press MODE to see all the settings you can adjust. The most common ones are at the top: "Normal" or "Sci" (scientific notation), "Float" or a number (how many decimal places to show), and "Radian" or "Degree" (which unit to use for angles). If you are doing trigonometry with degrees, make sure "Degree" is selected. If you are doing calculus or physics with radians, select "Radian".

Lower down you will see "Connected" or "Dot" (whether the graph is a smooth line or separate dots) and "Sequential" or "Simultaneous" (whether to draw graphs one at a time or all at once). For most homework, the default settings work fine. Change them only if your teacher asks you to or if the graph looks wrong.

The contrast of the screen can be adjusted if the display looks too light or too dark. Press 2ND and then the up or down arrow key. Holding the key makes the screen brighter or dimmer. This does not change any calculations — it only changes what you see.

Troubleshooting Common Problems

If you type something and see "Syntax Error", you made a typo or used a key in the wrong way. Press 2ND and ENTER to go back to the line you typed, and look for the mistake. Common errors include forgetting parentheses, using the wrong operation symbol, or pressing a key that does not work in that context.

If a graph does not appear or looks blank, check that you turned on the plot in Y=. Scroll to the left of the equation name and make sure there is a checkmark or highlight. Also check that your window is not zoomed in so far that the graph is invisible. Press ZOOM and choose "ZoomStandard" to reset to a normal view.

If the calculator is slow or freezes, press ON to turn it off and back on. If that does not work, you may need to remove the batteries for a few seconds and reinsert them. This clears the memory and restarts the calculator. You will lose any unsaved data, but the calculator will work again.

Frequently Asked Questions

How do I clear the home screen without losing my stored data?

Press CLEAR (above the DEL key) to erase the current line. Press it again to erase all lines on the screen. This only clears what you see — it does not delete stored variables, lists, or programs. To delete a specific stored value, press 2ND and +, choose the item, and press DEL.

Can I use the TI-84 Plus CE on a test?

That depends on your school or testing board. Most high school algebra and geometry classes allow it. The SAT and ACT permit graphing calculators, but some sections ban them. Check your teacher's rules or the test instructions before the day of the test. Some teachers ask you to clear the memory before an exam.

What is the difference between the 2ND key and the ALPHA key?

The 2ND key (blue) accesses the blue functions printed above each key. The ALPHA key (green) lets you type letters for variable names or text. Press ALPHA once to type one letter, or press it twice to lock it on so you can type multiple letters in a row.

How do I find the square root of a number?

Press 2ND and then ^ (above the ÷ key), which opens the square root symbol. Type your number and press ENTER. For example, 2ND ^ 16 ENTER gives you 4. You can also type a number and press 2ND and x² to square it instead.

Why does my graph look like a thick vertical line?

This usually means the window is zoomed in too far on one part of the graph. Press ZOOM and choose "ZoomFit" or "ZoomStandard" to see the whole picture. If the problem persists, check that you typed the equation correctly in Y=. A typo can create an unexpected shape.