Basics of Calculator Operation

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1. How do I make the home screen darker on the TI83?

Answer:
Step 1. Press the [2nd] key and then the up arrow key.
Step 2. Repeat step 1. over and over until the home screen is as dark as you want.
If this procedure does not make the home screen darker, then your batteries are probably low, and you should replace the batteries.

2. How do I make the home screen lighter on the TI83?

Answer:
Step 1. Press the [2nd] key and then the down arrow key.
Step 2. Repeat step 1. over and over until the home screen is as light as you want.

3. What would be an example of roundoff error?

Answer:
Consider the expression 1000(1+X-1)/X. A little algebra shows that this expression has the value 1000 for any X that is not equal to zero. However, if we try to compute this expression as written with the calculator, we find that the calculator gives the answer zero if X has the value 10^(-14). The reason is that the calculator will carry only up to 14 significant digits when it performs computations. When it computes 1+10^(-14), roundoff occurs, giving the result 1. The calculator next subtracts 1 to get zero. Division by 10^(-14) also gives zero, as well as multiplication by 1000.

If you suspect that a computation is being destroyed because of roundoff errors, you should try to rewrite the expression being computed. In the present case, we would use algebra to rewrite the expression simply as 1000 (when X is not zero).

4. How can I clear a drawing from the graph screen?

Answer #1. Press [2nd] , [DRAW] , select the option 1. ClrDraw , and then press [ENTER]. This will clear all drawings (such as shadings) and replot all functions that are turned on, as well as replot any stat plots that are turned on.

Answer #2. In the window menu, change Y_min or Y_max by a very small number.Then press [GRAPH]. This will clear all drawings and replot all functions (and stat plots) in essentially their same positions in the graph screen. (Thank you to VK for this suggestion.)

Answer #3. In the Y= menu, go to a function that is turned on and retype any letter or number in the function expression. Then press [GRAPH]. This will clear all drawings and replot all functions (and stat plots) in the graph screen.

5. When I plot the graph of tan(x) in the standard window, why does no graph appear?

Answer:
This is probably happening because the mode is set to degrees instead of radians. Go to the mode menu and make sure that the mode is set to radians.

6. Why does the calculator say "Error" when I enter the expression (-2-3)?

Answer: The problem is probably with the first minus sign. The first minus, a leading minus, should be a small minus (-), located at the bottom of the keyboard. The second minus is an arithmetic minus (a large minus), located on the right side of the keyboard. An error will also be generated if both minus signs are small. However, the expression (-2)-3, with both minus signs small, will compute as a product (giving plus 6).

7. When I turn on the calculator, I do not see a blinking cursor, and the screen is blank. Are the batteries dead?

Answer: The batteries are not necessarily dead. You should first try to adjust the contrast. With the calculator turned on, push the [2nd] button. Then push and hold the up arrow button. If the cursor comes into view, then the batteries are not dead. If not, then you probably need to replace the AAA batteries. Remember that the lithium battery (the small one) should also be replaced about every three or four years.

8. I reset the memory, and now the screen is blank. Did I damage the calculator?

Answer: Probably not. The contrast was reset to the factory setting, and this setting may be too low if your batteries are partly used. You should adjust the contrast to make the screen darker.

9. How can I find the 14 significant digits of a stored number?

Answer: Here is one possible method. We illustrate with an example. On the home screen, suppose we store the number 2^.5 into the variable X. The calculator will display 2^.5 as the number 1.414213562 on the home screen. Thus, we see 10 significant digits in the decimal approximation to 2^.5. Now enter the instruction X - 1.414213 on the home screen. This will remove 7 significant digits from the number in X and display the result as 5.623731E-7. We now see an additional 4 significant digits to the approximation to 2^.5. Thus, the 14 significant digits of 2^.5 are 1.4142135623731.

10. How do I enter the variable Y₁ onto the home screen?

Answer: Press the keys [VARS] [(right arrow)] [1] [1]. This sequence of keys will cause Y₁ to appear on the home screen.

11. I put new batteries into my calculator, and now the screen is completely dark. What happened?

Answer: Since your old batteries were weak, your contrast setting was at a high number. When you put in new batteries, the contrast setting was too high for the new batteries. You should lower the contrast setting by making the screen lighter (push [2nd], then push and hold the down arrow key). This will adjust the contrast to compensate for the strength of the new batteries.

12. I just typed in a complicated expression and realized I made a mistake. Do I have to retype the whole thing again?

Answer: No. Just press the [2nd] button followed by the [ENTER] button and the last expression you typed will be brought back to the screen for editing. Just change it to what you want it to be and you are done.

13. I was working on a group of computations about 5 minutes ago and now I want to look at them again. Is there any way to get them back?

Answer: Yes. The calculator keeps in its memory the last 99 expressions that you keyed in. If you keep pressing [2nd] [ENTER], you should eventually recall the computations that you were seeking.

14. I know that 9^(3/2) =27, but when I do it on the calculator, I don't get that answer. Why?

Answer: Exponents should always be in parentheses. If you type 9^3/2 the machine will compute (9^3)/2.

15. I type x^2+1 on the home screen and then press enter and I get the number 26, my neighbor does the same and gets the answer 1. Why are we getting answers here if we haven't keyed in any values for x?

Answer: If you have graphed any functions at all and moved the cursor, whichever was the last value of x that the cursor was on is the value of x that is stored in memory. So if you were at the origin the last time that you pressed trace, your value of x will be zero. While if you were at 5, your value of x will be 5.

16. How can I clear the memory of the TI83?

Answer: To clear the memory of the TI83 calculator, first press [2nd] [MEM]. This will give you the "MEMORY" menu of five options. Press 5 to select "Reset ... " . This will give you the "RESET" menu of two options. Press 1 to select "All Memory...". This will give you the "RESET MEMORY" menu of two options. Press 2 to select "Reset". After pressing 2 to select "Reset", the memory will be clear.
If the screen is very light or blank after clearing the memory, you will need to make the screen darker by pressing [2nd] and then holding the up arrow.

17. I have a program in my TI83 entitled "APROGRAM". How can I delete "APROGRAM" without deleting anything else?

Answer: First press [2nd][MEM]. This will give you a menu of options. Press 2 to select "Delete...". This will give you the menu entitled "DELETE FROM ...". Press 7 to select "Prgm ...". This will display the "DELETE:Prgm" screen and a list of your program names. Use the down arrow to move the cursor (>) to the name "APROGRAM". Then press [ENTER]. (On the TI-83-Plus, press the [DEL] key.) The program entitled "APROGRAM" will be deleted. All other programs will remain in the memory. Next, press [2nd][QUIT]. This will exit the "DELETE:Prgm" screen and display the home screen.

18. How can I transmit information from one TI-83 calculator to another TI-83 calculator using the "communication link"?

Answer: As an example, suppose we want to transmit the expressions in the Y₁ and Y₂ function variables from calculator#1 to calculator#2. To simplify this example, we assume that the variables Y₁ and Y₂ in calculator#2 are cleared. If not, clear any expressions in Y₁ and Y₂ in calculator#2.

Put the calculators side by side and insert the communication link cable into each calculator. (This cable was packaged with the TI-83 when it was originally purchased.) Turn on calculator#1 (if it is not already on) and press [2nd] [LINK]. The "LINK SEND" menu will be displayed. Use the down arrow to scroll to item "A" (Y-Vars) and press [ENTER]. This will display the "Y-Vars SELECT" menu, with no variables selected. With the selection cursor on Y₁, press [ENTER]. Use the down arrow to select Y₂ and press [ENTER]. The variables Y₁ and Y₂ are now marked with a small square box to show they are selected. Now press the right arrow key one time to display the "TRANSMIT" menu. Do not press [ENTER] at this time. Instead, go to calculator#2.

Turn on calculator#2 (if it is not already on) and press [2nd] [LINK]. Press the right arrow key one time to display the "RECEIVE" menu.

Now, in order, press [ENTER] on calculator#2. (The message "Waiting..." will be displayed on calculator#2.) Within one or two seconds later, press [ENTER] on calculator#1. Transmission will begin, and the message "Done" will appear on each calculator when transmission is finished.

Now press [2nd] [QUIT] on each calculator. Check calculator#2 to see that Y₁ and Y₂ have the correct expressions. (In calculator#1, the contents of Y₁ and Y₂ remain unchanged.) In a similar manner, other types of information can be transmitted between two TI-83 calculators. (Thank you to GI for suggesting this question.)




Related questions




Q1. How do I set up a function in the TI83?

Q2. How do I create a table of numbers using the Y₁ function?

Q3. How can I see more decimal places for the numbers in a table?

Q4. How can I delete the numbers in a table?

Q5. When I try to graph I get error "dimension". What does this mean?

Q6. My TI83 program will not stop running. It appears to be caught in an "infinite loop". How can I interrupt the execution of the program?

Q7. How do I stop the machine from graphing while it is graphing?

Q8. Can you give me some pointers on how to set up a good window to view a graph?

Q9. I try graphing y=(x^2-1)/(x-1) . The teacher says I should get something that looks like a line but I don't. What am I doing wrong?

Q10. I am in the standard window and want to get the cursor to the point on the curve where x=9. So I press trace and then the right arrow button a million times. Isn't there a faster way to get there?

Q11. I entered the expression (X^2)*(Y^3) into the Y₁ function variable. I then went to the home screen and stored the number 2 into Y. Next, I pressed [GRAPH], expecting to get the graph of 8*(X^2). Instead, I got the message "ERROR: INVALID". What happened?

Q12. How can I use the sequence mode functions u, v or w to generate a sequence, and then store the sequence in a list variable?

Q13. How can I use the "seq" instruction (in the LIST OPS menu) to generate a sequence, and then store the sequence in a list variable?

Q14. How can I "manually" create a list of numbers and store the list in a list variable?

Q15. How can I plot the five data points (4,2), (-3,4), (2,2), (-2,-1), (1,3) on the graph screen?

Q16. How can I compute a) cot ^-1(x) , b) sec ^-1(x) , and c) csc ^-1(x) using the TI-83 calculator?




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Frequently Asked Questions
Basics of Calculator Operation
Functions
Limits
Derivatives
Curve Sketching
Integration
Inverse Functions
Parametric Equations
Polar Equations
Sequences and Series
Vectors and Matrices
Functions of Several Variables
Multiple Integrals
Applications
Programs for the TI83
Problems Where the Calculator Gives an Incorrect Answer
Methods for Using the Calculator to Present Calculus Topics
Resources for Calculus Projects
Links to Other Calculus Sites
Reviews of Calculus Books, Web Sites, Etc
Calculus Forums
References to Articles on the Use of the Calculator in Calculus Courses
Final Examinations