Get to know your calculator early in any math course. Calculators are used for most routine arithmetic calculations now, and your ability to use a calculator will help to complete work accurately and efficiently.

While calculators come in many different makes and model numbers, most of them operate in similar manners. The notes here are specifically intended to assist you in becoming familiar with the Texas Instruments' TI-30X or TI-30Xa, but you should find the same function keys on many other scientific calculator.

For most algebra courses, you will need a scientific calculator. A scientific calculator includes functions for LOG, LN, and exponents, among other useful keys. It also performs arithmetic according to the Order of Operations (a calculator with only the arithmetic operations +, -,, and ¸ probably performs operations sequentially and is not useful for any advanced mathematical work). The TI-30X calculators are scientific calculators.

Do not worry if there are several keys you don't understand right now. This calculator will serve you well throughout your math courses, even to Calculus and beyond. Anytime you learn some new mathematics, try to learn how to use your calculator to go with it.

ON: Know how to turn your calculator on and off (the solar model has no OFF; there are no batteries to conserve). Some calculators have an automatic shut off if not used for a few minutes. On the TI-30X, the ON button is the top right key. This is also the All Clear (AC) button, which effectively gives you a clean slate to work with. AC clears the screen to "0", clears all memories, and turns off special features (like statistical mode). Use AC only when you want a fresh start. Avoid using AC in the middle of an exercise.

Primary functions: Every key has a number, operation or function name printed on top of the button. This is the primary function for that key. These are likely the ones you will use most often. The primary functions are grouped, more or less, according to purpose.

Numeric keys These are the keys for entering numbers digit-by-digit. Use the key for entering a number with a decimal point, like 2.57. Use the key to change the sign of a number from positive to negative, or vice versa. This is most useful for entering negative numbers: simply type in the number, then press to make it negative. It is important to use the negative sign after typing the number, because -0 is just 0.

These are the basic operations of (from top to bottom) division, multiplication, subtraction, and addition. These may be typed in the order written in an exercise, and the calculator will automatically perform the entire calculation according to the required order of operations once the key is pressed. Use the key only at the end of your calculation, and press it exactly once (no more).

Note that multiplication may be written with the symbols * or × as well as ´ . Multiplication may also be written with no symbol between numbers or parentheses; be sure to type in this case. Likewise, division may be written as ¸ or /. A fraction bar also indicates division.

Example 1. To calculate , type . The calculator will display the answer, 2.25.

Parentheses Include parentheses (as written) in any arithmetic exercise. The parentheses keys may be used for any pair of grouping symbols, including "(...)" or "[...]" or "{...}". Type the parentheses just as they appear in your exercise. You may also need parentheses at times when they are not shown. For example, a fraction with more than just a number in the numerator or denominator may be enclosed in parentheses for quick entry. Try to compute by typing .

The correct answer is 7.

Error correction Keys As described earlier, the button clears all previous entries and settings. Use this key when you start, but rarely afterwards. In the middle of calculations, is a better option. Pressed once, this key means "Clear Error". Use it to correct an incorrect number as you type during a longer entry. For example, suppose you are trying to calculate 28 (16) + 42, and you typed (but you notice this should have been 16, not 26). Press once to clear just the last number entry. Then type in the correct entry and the rest of the calculation: . You should get the answer 490.

If you typed well beyond the mistake, then press twice (to activate "Clear"). This clears the entire calculation from the screen, so you can start over. For example, in the above calculation, suppose you typed before noticing that the 26 should have been 16. Press and start over: .

One other option (and a good one), is to make use of the backspace key. This key erases only the last digit typed. Press it once or more to get back to the mistaken digit, and then resume your calculation. Having typed , press the backspace twice, then continue with 16 to get the correct answer. Note that the backspace will only erase digits, not operations.

Exponent and Root Keys Your calculator also has keys for performing any exponent calculations. The simplest of these is perhaps the key, which squares the number currently displayed on the screen. Enter the base number first, then press . The result is displayed immediately. Try 9² by typing ; the answer is 81. Try 16² on your own (the answer is 256).

The opposite of squaring is the square root. gives the square root of the number currently displayed on the screen. Try out and .

 gives the reciprocal of the number on the screen. Literally, this is 1 divided by x. Mathematically, 1/x is also the same as x^-1. On some calculators, the key is . For example, to quickly change 1/200 to a decimal, type . The screen will show 0.005. Likewise, to find 50^-1, type to get 0.02.

Finally, the calculator also has a key for doing more general exponents (all three of the above can be done with the exponent key, but they have special easy to use buttons because they are so commonly used). The exponent key is (find it just above the division key). Essentially, pressing this key tells the calculator that the next number you input will be an exponent for the number already on the screen. One nice feature is that the exponent can be any possible number (integer, fraction, decimal, or even another calculation enclosed in parentheses). Always enter the base number first, followed by the exponent key, and then the exponent. Press the key after entering the exponent (or continue the rest of the calculation if there is more). For example, find 2¹⁰ by typing (the answer is 1024). To compute 0.2^-3 type (answer is 125). Note that the negative exponent is entered by typing 3 followed by the key.

The memory keys allow you to save up to three different numbers for later use. To save the number currently on the display, type . This "stores" the value in memory cell 1 (replace with or to use memories 2 or 3, respectively). To "recall" a number stored in memory cell 1, use . To try this out, let's compute x² - 17x + 5, using the memory cell 1 for x when x = -3.217. First enter the number, change the sign to negative, and store it in cell 1 as follows: . Then type in the computation, using for each occurrence of the variable x:

Do not forget to include the "times" symbol between "17" and "x" in the middle term. The answer displayed should be 70.038089.

By substituting or for after , you can use up to three values for use in a single calculation. The memory cells are especially useful if you have a lengthy number (avoid copying and retyping) or if you expect to use the same number several times.

The Fraction Key Perhaps one of the nicest features of this particular calculator is its ability to work fraction arithmetic. When properly entered, the calculator will use fractions correctly in any calculation. First, you need to know how to enter a fraction.

Single fraction: Enter the numerator (top number), press the fraction key , then enter the denominator (bottom number). So the fraction is entered as . The calculator displays the fraction something like .

Mixed numbers: Use the fraction key twice. The mixed number is entered as . In short, simply press the fraction key between each number in a fraction or mixed number. Your calculator knows the difference. The mixed number is displayed as .

Now you are ready to use fractions in other calculations. Simply enter the fraction wherever it appears as you continue typing the entire calculation. For example, try computing by entering the following sequence:

The answer will be displayed as a fraction or a mixed number (if more than 1). In this case, you should get , which means .

Secondary Functions and the Key. You have probably noticed by now that the calculator also has writing just above each key. To save space, the calculator was made so that each key can perform two separate functions. The primary function is labeled directly on the key as is used simply by pressing the desired key (everything we have discussed so far is a primary function). To activate a secondary function, first press and then the key below the name of the desired function. A few commonly used secondary functions are, , and .

finds roots of any index. This is really just the opposite of the exponent key. Enter the number under the radical, press the key, then enter the index of the root. Press if finished, or continue the calculation. To compute , enter . Note that the key changes the meaning of the key to . You should get 12 for the answer.

Above the fraction key is the improper fraction function . This is nice for converting a mixed number into a pure fraction (although called improper, a single fraction with any numerator and denominator is usually easier to use in algebraic expressions than the equivalent mixed number). In the section on fractions, we did a calculation that gave the answer . This can be converted to a pure fraction by pressing , which activates the secondary function and displays the fraction . Written as a fraction rather than a mixed number, the answer is .

Another related secondary function is , above the backspace key. The label stands for Fraction-to-Decimal. By pressing this key, any fraction on the displayed will be changed to its decimal form. If the display is a decimal number, the calculator will try to write the number as a fraction, but this is not always possible. So if the decimal number remains, then there is no simple equivalent fraction (remember that the calculator can only do fractions with 3-digit numbers). For example, convert to a decimal just by pressing . You should see 4.6 on the display. Press again to change the answer back to fraction form (you get because the calculator prefers mixed number form). Press to get back to the pure fraction form .

Most everything else are keys you won't be needing until a College Algebra or Calculus course or beyond. You will learn about the keys for the logarithmic and trigonometric functions later. Most of the secondary function keys are used for probability and statistics.

Use a calculator to compute each of the following. When the answer is a fraction, give the answer in (a) mixed number form and (b) fraction from.

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