"Getting to know your calculator" lab

This lab is designed for you to become familiar with your calculators. We will be using several in this class. The TI-34 is small but has many capabilities. The more you know about it - the more confident you should feel. Let's get started! Work in groups of two.

Activity One : Open up your calculator. Look at the keyboard layout. Is there an on key? Why or why not? Record your results below.

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Type in a number, say 420, and press the AC/ON key. What happens? Type that same number again. This time press CE/C. What happens? What can you say is the purpose of the two keys (record the results below). You will probably want to get in the habit of using the CE/C key more. You will see why later.

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Let's try some simple operations to warm up. We are going to work on some keys you already should know. Compute the following with your calculator and record the results. (This will be a breeze!)

1) 123, 456 + 789, 012 =

2) 80, 000 - 456 =

3) 123.45 x 918.63 =

4) 189 25.3 =
5) 6 0 =

6) 2 3 =

Check with your neighbors to see if your answers are the same. Look at number 5. What did you think the answer was going to be? Explain why you got the answer you did below, maybe using a simple proof.

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Look at your answer for number 6, work that one out by hand below. Do you agree with the answer the calculator gives? Explain the difference between the answers.

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Activity Two: Now that you are figuring out some of the quirks of the calculator and how to interpret the calculators results, let's try some more.

First, you and your partner should discuss below how you could use the calculator to answer the following:

+

You are now going to learn how to add, subtract, multiply, and divide rational numbers. Look for a key labeled a . We are going to enter first. You need to first enter the numerator, next press the a key, and finally enter the denominator. Draw below what comes up on the

shows calculator's screen (it doesn't look exactly like what you are used to):

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Now you should be able to add + . Record your results below. What do you think it means?

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Your answer was a mixed number. Therefore, the calculator separates the whole number from the fractional part by displaying a "_". Now it is up to you and your partner to figure up how to add the following. Write down the entire procedure you used to answer the following below so you will have a reference for later (that means all the keys you used as well):

1 + 2

Procedure:

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Now that you are an expert at using the "fraction" key, try the following:

1) x =

2) =

3) x =

Check with your partner to see if you both agree with the answers. Can you explain below why you got the answer you did for problem 2? What about problem 3? Could you have answered problems 2 and 3 without using the fraction calculator? Answer below.

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Activity Three: Now you are going to use the calculator to generate patterns. You and your partner will decide how the calculator continues the patterns.

First, enter 5 + 1 and press "=." Write the answer below. Now press the "=" key again. Write down what you got next to the first answer. Now press the "=" key repeatedly and record the results below. What do you notice?

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Next, enter 100 - 4 and press "=." Write the answer below. Now press the "=" key again. Write down what you got next to the first answer. Now press the "=" key repeatedly and record the results below. What do you notice?

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Write a brief statement below that describes how you can use the calculator to generate a pattern of numbers.

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Now see if you can continue the following patterns using the calculator.

1) 3, 5, 7, 9, ___, ___, ___, ___, ___, ___, ___, ___.

2) 246, 267, 288, 309, ____, ____, ____, ____, ____.

3) 1001, 991, 981, 971, ____, ____, ____, ____, ____.

We can also use the calculator to generate multiples. What is a multiple? Define it below.

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To generate all of the multiples of two we will start with zero and add two. (Remember that zero is a multiple of all numbers.) If you continue to press "=" you will get all the multiples of two. You should have 0, 2, 4, 6, 8, 10, etc... Now you can generate the multiples of the following numbers. (Remember to start with zero.)

1) Find the first ten multiples of 3.

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2) Find the first ten multiples of 7.

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3) Find the first ten multiples of 12.

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Activity Four: Here is a good time to talk about a new key on your calculator. Look for the key with the arrow on it. It looks like this "->". I want you to enter a string of numbers to fill the screen. Now press the arrow key. Press the arrow key again. What could you say the function of this key is? When could it be of use to you? Explain below.

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Activity Five: Now it is time to talk about rounding. You may need to review by doing some rounding on your own.

Round the following and check with your partner to see if you agree:

1) Round 123.456 to the nearest tenth place.

2) Round 5.3481 to the nearest hundredth place.

3) Round 9.9999 to the nearest thousandth place.

4) Round 0.345 to the nearest whole number.

Did any of them give you problems? Which ones and why? Answer below.

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The calculator has the capability to round. However, the task is a bit complicated and you must still know how to round. It really comes in handy if your are going to be entering a lot of data that needs to all be rounded to a specific place value. Let us say we are working with our checkbook and want to round all of our answers to the hundredth place. Keep in mind that monetary amounts end in two numbers after the decimal place.

We can "fix" the calculator to round by pressing the blue bar labeled "2nd." What appears on the screen when you press the blue bar? What do you think the function of the blue bar is?

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Now that you have pressed the blue bar, press the arrow key. (You should look above the arrow key and written in blue will be the word fix.) Now we have to tell the calculator how many places should be after the decimal place. Since you are going to be rounding all of your answers to the nearest hundredth enter the number 2. What shows up on the screen? Draw it below.

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The one thing you will have to remember is that you will have to use the CE/C key to clear your screen from now on. Remember it was mentioned earlier that there was a difference between this key and the AC/ON key. Press the CE/C key now. What happens? Now press the AC/ON key. What happens? Repeat the steps to have the calculator round and we will see what happens. Don't forget to use the CE/C key to clear your screen from now on.

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Watch what happens when you enter the following number. The calculator has been fixed to round all of the numbers you enter to the nearest hundredth place. Enter the following and record the results.

1) \$12.033 rounded to the nearest hundredth place is __________.

2) \$12.875 rounded to the nearest hundredth place is __________.

3) \$ 0.999 rounded to the nearest hundredth place is __________.

Now using what you have learned, see if you can have the calculator round to the nearest tenth place. Remember how many numbers are after the decimal place when you fix it to round. Round the following to the nearest tenth place.

1) 12.05 rounded to the nearest tenth place is ___________.

2) 0.94 rounded to the nearest tenth place is ___________.

3) 0.99 rounded to the nearest tenth place is ___________.

Explain below how you and your partner would use the calculator to round numbers to the nearest whole number. Test your hypothesis to see if it works and explain the procedure below.

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Activity Six: It is now up to you and your partner to work together to reach a common answer. Decide the answer to the following problem. Explain your answer below (agree on one answer):

3 + 6 x 6 -12/3

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Did you and your partner come up with more than one answer? We really have to have consistency, and if you and your partner came up with different answers than we do not. Try entering the problem in the calculator using the following keystrokes. Fill in the blanks.:

3 + 6 = ____ x 6 = ____ - 12 = ____ / 3 = _____

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Did you or your partner come up with that answer? Is that the right answer?

You will investigate one other way to enter the problem. Think about whether you will get the same answer before you enter it. Enter the following problem as follows:

3 + 6 x 6 - 12 / 3 = _____

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Which key sequence do you think gives you the "correct" answer? Can you explain why? Before you decide, you may want to think about order of operations. (remember P.E.M.D.A.S)

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Now try the following using your calculator:

1) 20 / 2 x 4 - 10 + 15 / 3 =

2) 17 - 3 / 2 + 6 x 3 =

Activity Seven: We are now going to explore another way to utilize the calculator for a "shortcut." I want you to answer the following:

1) 7 x 7 =

2) 25 x 25 =

That was easy. However you had to use four keystrokes to come up with an answer. Do you remember a shortcut way of representing n x n? You and your partner should be looking on the keyboard for the exponent keys. (There are two.) One will raise a number, x, to the second power. Write down the key you think that is below.

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The other key with raise any number, y, to any power x. Write down the key you think that is below.

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To do problems #1 and #2 from above, you can use either key. However, if you are raising anything to the second power, it is much easier to use the key. All you need to do is enter the number, for example 7, and then press the key. You get the answer immediately. Try the following:

1) =

2) =

To raise any number to any power, you will need to use the key. For example, if you wanted to solve you would enter 7 - your base, then press the key. Then press 4, your exponent,
and finally press "=." You should get 2401. Create three exponent problems on your own and record the three problems you tried along with the answers below:

1)

2)

3)

Activity Eight: You are now going to play around on the calculator and record your results. Be sure when you go to the next problem to clear the screen using the AC/ON key to get rid of all functions. Write down what happens when you do the following:

1) Press the blue bar labeled "2nd" and then the key marked EXP with the symbol above it. What shows up on the screen?

_____________________________________

2) Enter the number 25. Press the blue bar labeled "2nd" and then

press the "=" key with the % symbol above it. What shows up on

screen?

_____________________________________

3) Press the blue bar labeled "2nd" and then the "." key with the

symbol SCI above it. Now enter the number 36000 and press "=."

What shows up on the screen?

_____________________________________

4) Press the yellow bar labeled "mode" and then press the number 4.

(You should see the word HEX on it.) Now multiply 4589 by 3698.

What shows up on the screen?

_____________________________________

Activity Nine: Now you are going to learn about another key on your calculator that can save you some time. However, I want you to see what happens before we use the shortcut.

Word Problem: Suppose you start a new job making \$4.75 an hour. If you work 20 hours, how much money will you earn before taxes?

Solution: .

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Another Word Problem: This week you worked 37hours. How much will you earn before taxes?

Solution: .

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That wasn't bad. However, there is a way to enter your salary into the calculator so that it is in its memory for a while. To do this you must look for the keys labeled STO and RCL. STO is short for store. We are going to store a number into the calculator's memory. To do this enter the number you want to store, in our case 4.75. Now press store. What did you see appear? What do you think it stands for?

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**IMPORTANT**

Remember at the beginning it was discussed that we could use two keys to clear the computer screen. We are going to use the CE/C key so it will not erase your number. You may press that key now.

Now that the number is stored, to recall that number you will have to press the RCL key. Press that key now. What showed up on the screen? Press the CE/C key.

We can use that stored number to create a table of hours worked and money earned. To find out how much you will make enter the number of hours multiplied by the RCL key.

EX) If you worked 5 hours: enter 5

press the X (times) key

press the RCL key

press the = key.

What did you get?__________

Now complete the following chart:
```Hours worked 	|    money earned

1

2

3

4

5

6

7

8

9

10

11

12

13

14

```
Congratulations, you are now an expert at using the TI-34 calculator. There are still many more applications for this calculator that you will learn. These pages will serve as your reference for later so do not lose them!