As somebody who has been in higher level math classes I’ve found it immensely helpful to have a good understanding of how to use a calculator. I doubt I would have gotten the grades I have if not for the little hacks I learned over the years. As I reach the end of my tenure at Lake Forest High School, I hope to pass on some of this knowledge to as many as possible. Many of you may already have students in your classes that already know how to use these functions and thus may have an advantage on tests. Some of you might already be familiar with some of these tips, but I still hope you can take something from it or pass it on to somebody who could use it.

I think it should be noted that the hacks should not be used as a supplement of knowledge on core material. Ideally, they should serve as a way to lessen and check work. Additionally, I never got to take computer science so I’m sorry if some of these aren’t coded nicely. That being said, they still work. If anybody has a better program for any of these functions please email me so I can update the page.

## Important Buttons

- A.
**QUIT (2ND, MODE):**The quit button is used to exit out of a current menu/screen - B.
**2ND:**The 2ND button is used to execute secondary buttons in blue. - C.
**ALPHA:**The alphabet button allows you to use the other keys as alphabetical buttons. The green letters above buttons correspond to the alphabetical buttons. You can lock the ALPHA button by using A-LOCK. - D.
**A-LOCK (2ND, ALPHA):**The A-LOCK button is used to type using the alphabetical buttons without having to press ALPHA before every character. Exit the A-LOCK mode by pressing the ALPHA button. - E.
**TEST (2ND, MATH):**The test button brings you to a menu that holds operators (i.e. =, <, >). - F.
**STO>:**The store button allows you to store something, often a numerical number, into a specified variable. - G.
**ON:**The on button activates your calculator - H.
**DEL:**The delete button deletes the existing character - I.
**ARROW KEYS:**The UP key moves the cursor up, the DOWN key moves the cursor down, the LEFT key moves the cursor left, and the RIGHT key moves the cursor right. - J.
**CLEAR:**The clear button clears the existing line, and also backs out of a menu. - K.
**PRGM:**The program button brings you to the programming interface. - L.
**MEM (2ND, +):**The memory button is used to delete programs or check storage. - M.
**ENTER:**The enter button submits or executes a commands.

#### Where to Find Certain Keys

- If, Then, Else, End, Stop: When writing the program hit the PRGM button and you will find these under the CTL tab
- →: Hit the STO> button
- Input, Prompt, Disp: When writing the program hit the PRGM button and you will find these under the I/O tab
- <,>, or =: hit the 2ND button and then hit the MATH button to find these

## 1) Evaluating Quadratic Functions

You can use this program to solve for the x’s of a quadratic equation. It functions through utilizing the quadratic formula but cutting out the work. I will go through a step by step of how to create this program into your calculator.

- Press the PRGM button
- Go to the tab called NEW and hit ENTER to create a new program
- Enter whatever name you want to call this program, for the purposes of this I’m going to call it “SOLUTION”, you can use the letters above each of the buttons
- This is when you start to enter the actual program, after each line press the ENTER button, you just need to enter it as it shows below

#### How to use this

- Enter whatever the value is for a, b, or c when it asks for each variable
- If there is a section where the equation is blank for one of the variables then you can enter 0 for whatever value is blank, Ex: x² + 1 = 0, enter a=1, b=0, c=1
- the answer is whatever the x-value is

PROGRAM: SOLUTION

:Prompt A, B, C

:B²-4AC→D

:If D<0

:Then

:Disp “NO REAL SOLUTIONS”

:Stop

:End

:If D=0

:Then

:Disp “1 DISTINCT SOLUTION”, ((-B)/(2A)) »Frac

:Else

:Disp “2 REAL SOLUTIONS”, (-B+√(D))/ (2A) Frac, (-B-√(D))/ (2A) »Frac

:End

:

## 2) Finding the Distance

You can use this program to solve for the distance between two points (a,b) & (c,d).

- Press the PRGM button
- Go to the tab called NEW and hit ENTER to create a new program
- Enter whatever name you want to call this program, for the purposes of this I’m going to call it “DISTANCE”, you can use the letters above each of the buttons
- This is when you start to enter the actual program, after each line press the ENTER button, you just need to enter it as it shows below

PROGRAM: DISTANCE

:Input “X1=”, A

:Input “Y1=”,B

:Input “X2=”,C

:Input “Y2=”,D

:Disp (√((C-A)²+(D-B)²))»Frac

:

## 3) Evaluating the Slope

You can use this program to solve for the linear slope of the line between two points (a,b) & (c,d).

- Press the PRGM button
- Go to the tab called NEW and hit ENTER to create a new program
- Enter whatever name you want to call this program, for the purposes of this I’m going to call it “SLOPE”, you can use the letters above each of the buttons
- This is when you start to enter the actual program, after each line press the ENTER button, you just need to enter it as it shows below

PROGRAM: SLOPE

:Input “X1=”, A

:Input “Y1=”,B

:Input “X2=”,C

:Input “Y2=”,D

:Disp ((D-B)/(C-A))»Frac

:

## 4) Finding the Midpoint

You can use this program to solve for the midpoint between two points: (a,b) & (c,d).

- Press the PRGM button
- Go to the tab called NEW and hit ENTER to create a new program
- Enter whatever name you want to call this program, for the purposes of this I’m going to call it “MIDPNT”, you can use the letters above each of the buttons

PROGRAM: MIDPNT

:Input “X1=”, A

:Input “Y1=”,B

:Input “X2=”,C

:Input “Y2=”,D

:((A+C)/2)»Frac→X

:((B+D)/2)»Frac→Y

:Disp “(X+Y)”

:Disp X,Y

:

## 5) For When You’re Storing Values

- For when you want to assign a numerical value to a variable on your calculator
- For example let’s say that you want the letter “B” to equal 74.
- You would do this by entering the following into your calculator:

74→B

- From now on until it is reassigned that variable will equal that number

## 6) Saving Those Equations

- You can do the same with #5 but for equations
- You follow the same formula but you need to set the variable equal to a function you have in your Y=
- Let’s say that you want the letter “C” to equal an equation you have written out in your calculator to graph in the Y1 slot. You would do this by entering the following:
- Hit the ALPHA button and then hit the TRACE button, scroll to which Y# slot your equation is

Y1→C

- From now on until it is reassigned that variable will equal that number

## 7) The Magnificent STAT button

- You can turn data points into different types of functions
- Can be used to find the best fit line
- Given a set of points it can be used to find what trend they follow (linear, power, exponential, etc.)

- Hit the 2ND button
- Press the 0 button (into the calculator catalog)
- Scroll down to DiagnosticOn and hit ENTER

This will allows you to see how similar the best fit line found is to the actual function created by the data points. The closer the r² is to 1 the more accurate the equation found is.

**Helpful Link**: http://www.instructables.com/id/Programming-using-the-TI-84-Plus/

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