Excel Exercise 2 Using Formulas

Excel Exercise 2 Using Formulas Mathematics 133 Section 001/L01 General Information File Name: Name the workbook: Lab2-YourName Do not use spaces in the file name. Header: In this and all future exercises, attach a header with your name on the left, Math133 in the middle, and the number and title of the exercise on the right. (If you are unsure how to do this, look at the directions from the first Excel Exercise.) Formulas: The real strength of spreadsheets is shown when we use formulas. For a general introduction, you might look at some of the Excel links given on the course homepage. Starting an entry with an equal (=) sign tells Excel that you are entering a formula. Within the formula, you can use arithmetic operation +, -, * and / and exponentiation ^. You must use parentheses for complicated formulas (Excel uses the standard mathematical hierarchy of operations). Thus, for example, entering =3+4^2 in a cell would produce 19. (Try it!) Note that even though you've produced this as output in your cell, if you select the cell, the formula which produced the output will be visible and can be edited in the formula bar. Most importantly, you can refer to other entries in the worksheet by their addresses, such as A1 or E7. For example, if the number 3 was in cell A1, 4 was in A2, and 2 was in A3, the typing =A1 + A2^A3 in cell C4 would again produced a 19 in that cell. Note what happens, however, if you change the contents of one of the cells; for example, let's put a 7 into A1. When you hit Enter, Excel updates all calculations involving A1. In particular, C4 should now contain 23. (Because 7 + 4^2 = 23.) The key feature to understand is that these addresses are relative. Continuing with the above example, select cell C4 (the one with the formula) and using the Edit menu or your

mouse or control keys, copy the contents onto the clipboard and paste it into E6. The formula in the cell should now read =C3 + C4^C6 which will calculate to 1. (Any empty cell is presumed to calculate a zero, so you are doing 0 + 23^0 = 1.) Excel did not really know that your formula in C4 was referring to A1, only that it was referring to the cell two columns to the left and three rows up. In other words, what Excel really has in C4 is the formula =(two left, 3 up) + (two left, two up)^(two left, one up) This feature is incredibly powerful when you want to do the same computation repeatedly to whole bunch of different inputs. Sometimes, however, you want to refer to a cell in an absolute way. You must indicate this by using dollar signs to "fix" the row and column. Continuing with the same example, select C4 again and edit the formula to read =$A$1 + $A$2^$A$3 Now copy and paste this formula into any cell, like G4; notice that the formula has not changed this time. Finally, you can combine absolute and relative references. For example, for an absolute column and a relative row reference, use $A1 and if you want the row reference to be absolute but not the column reference, then use A$2.) Try changing the formula in C3 to =$A1 + $A2^$A3 and to =A$1 + A$2^A$3 and pasting it two other cells.

Exercise 2 1. Work through the above series of examples; do not hand them in. 2. Make a simple sales tax table. Format the table as you feel is appropriate, using the techniques from Excel Lab 1. 3. Display the Fort Collins sales tax rate of 6.8% in a cell and label it as such. 4. Begin making a tax table: label three adjacent columns with "Amount," "Tax", and "Total." In the amount column, enter purchase amounts of $5, $10, $25, $50, $75, $100, $250 and $500. 5. Use a formula to compute the sales tax on these amounts in the adjacent column. 6. Finally use a formula to compute the total amount of price plus tax in the next column. Hint: If you use absolute and relative references correctly, you will only have to type two formulas: one for each calculated column. You can fill in the rest using cut and

paste or auto fill. (Select the cell that contains your formula and, with the cursor positioned in the lower right cell corner, hold your left mouse button down and drag the mouse to highlight the column. When you release the button, it should auto fill using the appropriate references, if you used relative and absolute addresses correctly. Also, if you change the tax rate, for example to 6.5%, all of the numbers should automatically adjust. 7. You must EMAIL a copy of this exercise to the instructor. Tips: •

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Generally, after you enter a formula, it calculates the value and displays that value; i.e., the formula disappears from the screen, To read the formula, select the cell; the formula will appear in the formula bar. If you want to see all of your formulas displayed, go to the Tools menu, select Options, then View and the check the box next to Formulas. The calculated values will disappear from your sheet and the formulas will reappear. To reverse this process, simply uncheck the box. Rates should be displayed as a percentage. To do this, select the cell the rate will appear in and click the % box in the tool bar. Now when you enter a number, say 7, Excel displays 7% but uses .07 in calculations. By default, Excel seems to assume it should round percentages to the nearest percent. To change this, select a cell with the percent style, go to Style in the Format menu and click Modify. You will see a place to change the number of places. Of course, you can always convert the percent to decimal and enter that number instead. Similarly, dollar amounts should be displayed with a dollar sign. Rather than typing the $ in each box of that column, use the $ button on the tool bar. This can also be done by right clicking on the cell and choosing the format of the number. If you see ##### appearing in a cell, it means the cell is not wide enough to display the result of the calculation. Use the skills you learned on the previous exercise to adjust the size of the cell.