Working with Fractions on the TI-73 Graphing Calculator

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Kristopher Johns
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1 Working with Fractions on the TI-7 Graphing Calculator The TI-7 graphing calculator has as a major feature the ability to handle working with fractions without the need to translate them into decimals. This allows students to explore fraction concepts and compute easily with fractions.. Entering fractions on the TI-7 Typing fractions on the TI-7 is fairly intuitive. Let s take a look at several fractions and the keystrokes needed to enter them into the calculator. Example : + First, clear your home screen by pressing :. Next, type in the fraction by pressing Y=Z. To complete the fraction, press the right arrow key ". Then press \and type in the fraction by pressing Y=Q". To complete the computation, press b. The result,, appears as a fraction. Example : 7 5 You may clear the home screen if you choose. To enter a mixed number, first type the whole number portion, YThen press <to indicate you that many whole units. Then type in your numerator in the space provided. To get to the denominator, press the down arrow #, or you can press the = key. When you are done entering your fraction, press the right arrow ". Continue by pressing the multiplication sign, and then Monroe County ISD, Michigan Page of 6

2 7 entering 5 in the same manner. Press b when you are ready to perform the calculation.. To automatically simplify fractional results or not? The default mode of the calculator has all fractions simplified (reduced) automatically. After all, that is the way fractions are typically used in simplest form. But, you may at times want the calculator to NOT simplify your results. If you press your. key, you will see: Autosimp is highlighted, as is Aub/c so the calculator automatically simplifies results. You can manually simplify results or see results as improper fractions by choosing Mansimp and b/c instead. To do this, move your cursor down using the down arrow to the rd line, then move to the right so b/c is flashing. Press b. The calculator is now set to leave fractions as improper fractions. Next, use your down arrow to move to the bottom row. Highlight Mansimp and press b. Now the you ll have to simplify the fractions yourself. These settings will remain in effect until you change them back, or until the calculator is reset.. Why would I ever want to manually simplify the results? When working algebra problems, for instance, sometimes it is permissible to leave your answers as an improper fraction, but with any common factors of the numerator and denominator removed. Also, teachers may want students to see the variety of ways some fractions can be simplified. 7 5 Example : Calculate +, and then write your answer in simplest form, 6 stating by which factors you reduced your answer. Step : Set your calculator to Mansimp and b/c as shown in # above. Step : Type in the addition problem above. Press b. Monroe County ISD, Michigan Page of 6

3 This is what you should see: The big question is, Can be simplified? If you press Band then bthe calculator will try to remove any common factors (other than, of course). It will even tell you what the largest factor it finds in common (GCF) between the numerator and the denominator. In our case, no such luck. is prime. We can at least write the improper fraction as a mixed number. Press? and? and the calculator will automatically divide the numerator by the denominator (top bottom), write down the number of whole units it finds, and put the remainder over the denominator as the fractional part of the mixed number. Your screen should look like this: You can also choose by what factor a fraction is simplified. Example : Reduce to simplest form. Step : Type into the calculator. Step : Press Band then type the number you d like to divide numerator and denominator by; in other words, pick a number you think is a common factor. You can simplify repeatedly if your numerator and denominator share several common factors or repeated factors. A fun game is to see how quickly you can simplify fractions by picking the GCF the Greatest Common Factor. Monroe County ISD, Michigan Page of 6

4 . Moving between fractions, decimals, and percents. It s very handy in day-to-day life to be able to move between fractions, decimals, and percents. They are just different ways of expressing similar ideas. fractions: expressing wholes, and parts of wholes decimals: expressing wholes, and parts of wholes using powers of 0 (tenths, hundredths, thousandths, etc.) percentages: expressing wholes and parts of wholes, using a denominator of 00 only. Out of 00 is what percent actually says. a. Fractions to decimals and vice versa Pick a fraction and type it into your calculator. Then press >. That s the fraction to decimal button. Since the arrow goes both directions, you can start with either one and end with the other. Then press b. You ll see the decimal form of that fraction. Pick a decimal, up to decimal places. Type it in, then press > b. The decimal appears in fractional form. If you didn t change your calculator back to Autosimp(lification), it did not reduce the fraction for you. If needed, you can just press B and the calculator will do it for you. This same technique works with mixed numbers as well. b. Percents If you have a percent and want to know what it is as a decimal, just type in the percentage followed by the C key. Then press C. The calculator will display the percentage in decimal form. If you have a percent and want it in fraction form, type it in with the Cand then press >. If needed, change it into a simplified fraction by using B if needed. If you have a fraction and want it as a percent, you can change it to a decimal, and just move the decimal point mentally places to the right. Or, you can change it to a decimal and then multiply by 00 using the calculator. Monroe County ISD, Michigan Page of 6

5 Now that you know how to use the fraction features of the TI-7, try these. A. Write in simplest form B. Write in simplest form, using the Mansimp mode. Record at least factors you chose to simplify by, in the order you used them C. Complete the table. # Fraction Decimal Percent % % D. Change to a mixed number OR to an improper fraction Monroe County ISD, Michigan Page 5 of 6

6 E. Solve. Write results in simplest form (reduced and with mixed numbers if needed) ( + ) F. Compare. Use >, <, or = G. Write in order from least to greatest. If you change the form of any number, write the form you used..,,0.5,0., 5. 5,.56,,.65, 6. Draw a number line and place the numbers from # on it. Monroe County ISD, Michigan Page 6 of 6

Chapter 1 & 2 Calculator Test Study Guide

Chapter 1 & 2 Calculator Test Study Guide Powers and Exponents 1) To put a number to the second power, simply hit the x 2 key, then enter. 2) To put a number to the third or a higher power, key in base,