• Christian Paul

15 Tips & Tricks To Make Using Your Ti-nSpire CX CAS A Little Easier!

The newest calculators have been around for a few years now, but they are still pretty scary! Have a look at some of the basic tricks you can use to make your life a little easier.

These fancy schmancy calculators are the bane of your existence, am I right?! Whether you’re a teacher or student, the damn thing is confusing. Gone are the convenient little green calculators with obvious buttons for everything.

Why can't we keep using these?

Now we have these huge scary-looking CAS calculators with so many buttons, and so many pages and wonders that we don’t even know where to start. It’s quite a daunting task, getting to know this little piece of hardware. The good news is, if you can master the basics you’ll find that the new calculators have an incredible potential to get you through maths. So here is a list of just a few of the basic things you can do with your new toy that might make it a bit more bearable.

1. Quick copy and paste

You can press UP on the mouse pad to scroll up through your history of calculations. If you want to quickly copy something down to the entry line (for example an answer from a few calculations ago, or a formula you might have made a small mistake in), you can simply press ENTER while it is highlighted. This will copy the highlighted section directly down to the bottom line ready to be edited.

2. Save a number to a letter

If you are working through a complex problem, sometimes you find an answer that you know you will need later on, and sometimes multiple times. You can save this number under a name of your choosing, which could be anything from a to TheAnswerToQuestion3PartB. To do so, simply enter the number in or copy the number in question to the entry line, then use the STO→ function by pressing CTRL and then VAR on the top line of buttons just under the trackpad. A small arrow pointing right will appear, after which you type the name you want to save to. The names are not case sensitive (X is the same as x), so probably best to stick with something simple. Once saved, you can use it whenever you want just by typing the same name, or by selecting it from the variable menu (found by pressing VAR without pressing CTRL first). When you type the name of a variable, you will know something is saved because the font becomes bold on your screen.

3. Define a function

Let’s say a question gives you a function that you know you are going to do a lot of work with. Maybe you will be substituting in several values, using it for graphing or modelling questions, or using it repeatedly in a calculus question. The calculator can store a function that can be used in a huge variety of situations, but the most helpful one is substituting values. To define a function, press MENU → ACTIONS → DEFINE… and then type your function using the following notation: f(x)=3x+2

Once you press enter, the function will be saved and can be called by simply typing f(x). However, it is far more useful to use the function notation to sub in values. For example, typing in f(3) will substitute 3 in for x. Typing in f(a²-17) will work as well, and the answer will even come simplified! You aren’t tied down to using f as a function name either. If you choose to define a function as Meaningoflife(x)=42 you are more than welcome to.

These things are pretty cool…

4. Substitute a value on the fly

An alternative to defining a function is to sub in values on the fly. This can be done with the use of the “given” symbol, which in Maths is simply a vertical line: |

This symbol can be found by pressing CTRL followed by the = symbol directly below the little blue button. This will bring up a small menu on the screen, and the | symbol should be on the bottom right. By using this symbol, you can define the value of any letter as it appears in your formula. You just place the symbol at the end of the line and then use it to give the calculator its instructions. For example:

3x²-7x+2|x=4 will evaluate the expression while assuming x is equal to 4. You can also use this symbol to restrict the domain of a function.

5. Use basic computer shortcuts

The calculator can support basic computer shortcuts such as Save (CTRL+S), Copy (CTRL+C), Cut (CTRL+X), Paste (CTRL+V) and Undo (CTRL+Z). You don’t even have to press the two buttons at the same time, as the calculator registers a press of the CTRL button and then waits for your next input.

6. Sort a list of numbers

If you use the Lists & Spreadsheets page, the calculator can sort a large list of numbers quickly for you. Simply input the numbers in any order in a column, highlight the column (Go to the column name and then press up once more), then choose the Sort option from the menu. You will be able to choose Ascending (lowest to highest) or Descending.

7. Save Documents

The Ti-Nspire works similarly to a computer. It can save and open documents, which can be great if you study several different maths subjects or use your calculator for other purposes. Each document can have up to 50 open pages, with its functions saved, history and settings. That means you can have different settings set permanently for Methods and Further for example. Starting a New Document will erase everything unless you have saved the document. You can do this either from the DOCS menu or by pressing CTRL+S. You can also press DOCS to see what other documents you have saved.

8. Quickly move back and forth between open pages

Having multiple pages open can be very convenient for larger-scale problems, especially when working in data analysis or graphing questions. You can use CTRL+Left and CTRL+Right to scroll back and forth between your open pages. if you have a large number of pages open, you can also use CTRL+Up to zoom out to a summary page, which allows you to quickly navigate through your pages as thumbnails and jump to the one that you’re looking for.

9. Force calculator to answer exact or decimal form.

This is found in General Settings, which can be accessed from the home page. Once the Settings window is open, move down to the Calculation Mode setting. There are three options:

Auto: Gives exact answers unless a decimal was used while inputting the calculation

Exact: Always gives exact answers

Approximate: Always give decimal answers

10. Convert answers to decimal without changing settings

If you are studying Methods or Specialist Maths, you will likely need your calculator set to Exact or Auto most of the time, as you are usually required to give exact answers to most questions. However, now and then you will need a decimal answer, and it’s nice that there is a quick way to find it without changing the settings. Simply pressing CTRL+ENTER when evaluating an expression will force the calculator to give a decimal answer, even if your calculator is set to Exact.

11. Use a mouse

This calculator is so much like a computer, it makes sense that it would have a mouse as well! Simply run your finger gently over the trackpad a few times until the mouse pops up on the screen. You can use it to do mousey things.

12. Drag labels out of your way on a graph

If you work with multiple graphs and start analysing intersection points and the like, your screen will likely fill up very quickly with overlapping labels and text that can get difficult to read. If you find labels are tending to appear in the wrong place, just use the mouse to move them to a more convenient location. Position the cursor over the text, and a small hand should appear. If you press down on the trackpad and hold, the hand will close. You can now use the mouse to move the label anywhere on the screen, and simply click again to release it. You can finally declutter your screen!

13. Right-click (contextual menu)

Having a contextual menu is very convenient. It’s a smart menu that shows options related to what you happen to be working on at the time, and is akin to “right-click” on the computer. TI-Nspire calculators have this menu available as well, and it can be accessed by pressing the CTRL+MENU buttons. This will bring up a small menu with useful options including things like changing a graph colour or type, clearing a screen or hiding a particular element in a page.

14. Press-to-Test mode

This point is more of a warning than a tip. TI-Nspire Calculators come with a built-in restriction mode called Press to Test. It’s designed to limit the functions of the calculator during a test, the most important of which is the Solve function. Press-to-Test isn’t used by teachers in VCE, but students often activate it by accident because their calculator is rattling around in their bag without the case on the front.

The mode is activated simply by holding down the ESC key while turning the calculator on, and once activated it can’t be deactivated without access to either a second calculator (that doesn’t have Press to Test active) or a computer. You can recognise Press to Test mode because the calculator will throw up annoying notifications every time you wake the screen up, and a small light on the top of the calculator which will flash either yellow or green (next to the charging port).

To deactivate Press-to-Test you can do one of two things. You can connect your CAS to a friend’s using a USB cable, which will unlock the exit test mode option. Once the two calculators are connected, navigate to My Documents on the locked system (found in the Home screen), and once there press the DOCS button. Option 9 should be Exit Test Mode, which will instantly deactivate the restriction.

If you don’t have a friend’s calculator handy, or you don’t have access to the required cable, you can also connect your calculator to a computer and follow the instructions on the TI-Nspire website.

15. Draw something beautiful

If you can’t use your calculator to draw something pretty, what’s the point? There are thousands of functions in Mathematics which can demonstrate natural beauty. There is a certain degree of art in Maths, and discovering it is where my passion stems from. One of the more well-known ones is the butterfly curve. Give it a try! To start, open up a Graph page from the home screen. Once in, press MENU → GRAPH ENTRY/EDIT → POLAR. Open the entry line by pressing TAB if you can’t already see it, and you should have a two-line input.

On the first line: r1(θ)= exp(sin(θ))-2*cos(4θ)+(sin((2θ-π)/24))^5

On the second line: 0<θ<24π, θstep=0.13

This is just one way to create beautifully complex patterns using Maths. And one of the reasons I have such a passion for numbers. Maths doesn’t have to be all problems and confusion. There is art here as well 🙂

And much more!

The calculator has hundreds of useful functions built-in, which can do anything from finding an average of a list of numbers to working out repayments on a mortgage. Exploring is the best way to uncover these secrets. There isn’t a way to “break” the calculator in exploring. The worst you could do is accidentally activate Press-to-Test, or run a calculation complex enough to make the system lag. Which is an easy fix using the Reset button on the back of the handheld.

Happy exploring!

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