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Entering Expressions Practice Problems
Negative Numbers Squaring a Negative Number
Sharp EL531R
You will be absolutely amazed at how much work this calculator will save you. It probably cost you less than $20.00 and it will save you hours, no days, of work.
With very little effort you can learn to use your Sharp EL531R calculator to calculate what would otherwise be difficult or tedious mathematical problems.
By the end of this Tutorial, you will be able to:
Please have your calculator with you as you work through this lesson. If you look at buttons on your calculator, you will notice each one has something written on it and that most of the buttons also have something written immediately above them (usually written in yellow). If you merely press a button, it does what is written on it. For example, press the red [ON/C] button. (Long fingernails? Click here.) Your calculator comes on. If you first press the yellow [2ndF] button before pressing another button, the second button does what is written above it (usually in yellow) instead of what is written on it. For example, notice that above the red [ON/C] button it says "OFF" in yellow. Press [2ndF] then [ON/C]. This turned your calculator off. (I hope you are doing this on your calculator as you read.)
Important Note: 
Turn your calculator back on. It is important to know what the things on the calculator screen mean. Your screen probably has a "0." written on it. You know what that is. That is your inlaws IQ. But if you look real close, you will also notice that near the top of the screen is a very small "DEG," "RAD," or "GRAD." Two buttons below the [ON/C] button, you will find a [DRG] button. DRG stands for degrees, radians, and grads. If you press this button repeatedly, you will see that your screen cycles between "DEG," "RAD," and "GRAD." This only affects trigonometric calculation, which we will not use in this course. We just want you to know what the things written on your screen mean.
Notice that above the [DRG] button it says "MODE" in yellow. Your calculator is always in one of three modes: normal, onevariable statistics, or twovariable statistics. Press [2ndF] [DRG] and your calculator will ask if you want mode 0, mode 1, or mode 2. Press [1]. Notice that now your calculator screen has a black rectangle with the "STAT" written in light gray in the rectangle. That rectangle tells you that your calculator is in one of the two statistical modes (either onevariable or twovariable). The absence of that rectangle tells you that you are in normal mode. Press [2ndF] [DRG] [0]. We will use the normal mode (mode 0) for the beginning of this class. We will use the singlevariable mode (mode 1) for the latter part of Module 1 and all of Module 2. We will use the twovariable mode (mode 2) for Module 3.
Your calculator displays answers in one of four ways: floating decimal, fixed decimal, scientific, or engineering. Turn on your calculator and make sure it is in mode 0.
Press 2 [÷] [3] [=]
Your screen probably reads: 0.666666666
Press [2ndF] [.] notice that now it says "FIX" on the top of your screen. If you are my age, get out the bifocals.
Press [2ndF] [.] again and the "FIX" is replaced by "SCI"
Press [2ndF] [.] again and the "SCI" is replaced by "ENG"
Press [2ndF] [.] again and there will be nothing where the "FIX," "SCI," or "ENG" used to be. This means you are in the floating decimal display.
So, pressing [2ndF] [.] repeatedly cycles you through the four types of displays.
[If you are having problems with this, click here.]
Cycle the calculator to the FIX display.
In this display, answers are rounded to the number of decimal points you display.
To specify the number of decimal places you want:
Press [2ndF] [+/–] [3] for 3 decimal points
Press [2ndF] [+/–] [6] for 6 decimal points.
Pressing [2ndF] [+/–] while in "SCI" or "ENG" also changes the display. Because we do not use "SCI" or "ENG" in this class, we won't go into this. Before going on, put your calculator back into the floating decimal display using [2ndF] [.]
There are four cursor buttons between the yellow [2ndF] key and the red [ON/C] button. Best to learn this by example. Make sure your calculator is on, in mode 0, and in floating decimal display.
Press [2ndF] [DEL] this is to clear everything out of your calculators memory
Press [8] [7] [6] [times] [3] [2] [=] and you should get 28032
Press [3] [5] [2] [times] [1] [4] [=] and you should get 4928
Press [2] [5] [6] [÷] [3] but whoops now you realize you didn't mean to press 256 you should have pressed 296.
Just press the left facing arrow 3 times [<] [<] [<] so that your cursor is just to the right of the 5
Press [DEL]
Then press [9]
Press the right facing arrow 2 times [>] [>]
then press [3] [=] and you will get 98.66666667.
Now, we could use the left facing arrow to go back into our 296 ÷ 3 expression, but instead push the upward facing arrow [^] once and you will see that we instead went to the earlier expression of 352 times 14 which we could modify and recalculate. Or, we could push the upward facing arrow [^] again and we would get to our first expression 876 times 32. The downward facing arrow (V) would move us back down to 352 times 14. If we press it a second time (V), we return to our 296 ÷ 3 expression. This is all really cool but to be honest with you, I don't use the cursor keys much. It is good to know what they do.
Calculators have improved a great deal over the years. It used to be that if you wanted the square root of 9, you would press 9 then the square root button. Now if you want to know what the square root of 9 equals you press the buttons in the same order as you would say or write it. You would press the square root button then the 9 button then the equal button.
Also, on older calculators you would solve a complicated problem by solving a number of substeps then put them all together. For example, to solve 3 X 5^{3} + 24 X 2^{6} = , on an older calculator you would first find that 5^{3} = 125, then you would multiply that by 3 to get 375. This number you would write down or put into memory. Then you would work the other half of the problem 2^{6} = 64, and 64 times 24 is 1536. You would then add the 375 to the 1536 and you would get 1911.
On newer calculators like yours, you just type in the entire problem and solve it all at once: [3 [X] [5] [y^{X}] [3] [+] [2] [4] [X] [2] [y^{X}] [6] [=]
You get the same answer, 1911 (the year I was born). What you typed in remains in the upper half of the display screen. You can review it by moving the cursor keys. Your new calculator uses the same order of operations that you just read in your textbook. Sometimes, it helps to add parenthesis. For example. If you wanted to solve it helps to put parentheses around the numerator . Otherwise, you might accidentally be solving the equation
Solve Check answer by clicking here
Solve Check answer by clicking here.
It is important not to confuse the negative button [+/–] (which is next to the [=] button) with the subtraction button [—] (which is just above the [=] button). If you want to multiply 3 by –5, press [3] [X] [+/–] [5] [=]. Using the subtraction button instead of the negative button is very insidious. It will sometimes work and at other times it will give you a totally wrong answer (especially when we get to Module 3).
Hopefully you know that a negative times a negative is a positive. You also know that if you square a negative number you get a positive number. However, on scientific calculators (whether a Casio, Sharp, or Texas Instruments) if you enter a negative number and then square it, you will get a negative. Let's try it. Let's square a negative two [+/–] [2] [X^{2}] [=]. See, you get –4, not +4. Your calculator is treating this as –(2^{2}) while you really want (–2)^{2}. You will get the answer you want by pressing [( ] [+/–] [2] [ )] [X^{2}] [=] and you will get a positive 4.
That is it for the calculator until we get into statistics.