Module 0  Getting Acquainted  
Introduction  Lesson 1  Lesson 2  Lesson 3  Lesson 4   
Lesson 0.3: Entering Arithmetic Expressions  
In this lesson you will enter, evaluate and edit arithmetic expressions involving temperature conversion. We will use the TI83 Plus in this course. Most of what we do in this course can be done with either calculator. Occasionally we will point out the differences. We will refer to both models as the TI83 generically. The TI83 calculator is a useful tool for evaluating arithmetic expressions. One reason is that the display allows for eight lines that hold up to 16 characters each. This permits you to see both the problem and the solution. Another reason is that you can edit a previously entered expression to produce a new result. Evaluating an Expression There are several ways in which an expression can be evaluated. The following examples, which you should work through, provide direction on how to evaluate an expression at several values using different methods. The goal of the example is to find Celsius temperatures given Fahrenheit temperatures. Follow the directions in each example and note the differences among the methods used. The equation for conversion from Fahrenheit to Celsius is C = (5 / 9)(F  32) . Enter the Expression Method
The result shows that 90°F is approximately equal to 32°C.
Using the Negation Key The negation key and the subtraction key are slightly different in the calculator display. This result shows 19°F is approximately equal to 28°C. Editing a Prior Entry Rather than entering the entire expression (5 / 9)(30 32), you can edit the previous expression. The shape of the cursor should be a rectangle, which indicates the calculator is in the overwrite mode. The Celcius temperature that corresponds to 30°F is about 34.5°C Rather than entering the entire expression (5/9)(1932), you can recall the expression (5/9)(1932) on the Home screen and delete the negative sign. The expression (5/9)(19  32) is the second to last expression you entered in the calculator. You can perform the recall feature twice to paste the expression to the Home screen so that it may be edited. 19°F is about 7°C. Recalling the Original Expression You can recall and edit the original expression (5/9)(9032). The calculator changes back to overwrite mode after pressing . Observe as the cursor is once again a rectangle. Clearing Entries


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