TI-Nspire allows you to generate lists of sequential data very quickly in the Lists & Spreadsheet application. And the analysis of these data sets can be performed quickly and efficiently as well. If you are familiar with spreadsheets, you can draw on this past experience.
A recursive formula is a formula that is used to determine the next term in a sequence by using one or more of the preceding terms. The Fill Down command can be used to generate a recursive sequence in the case where you always use the previous term to obtain the next term.
Consider that you want to explore the future value of a $1,000 deposit under two different scenarios. Under the first scenario, you earn 5 percent annual interest. Under the second scenario, you simply add $100 each year to the account. Here’s how it’s done.
Type the initial deposit, 1000, in cells A1 and B1.
Type =a1*1.05 in cell A2 and =b1+100 in cell B2.
Move the cursor to cell A2 and press [MENU]→Data→Fill to grab the cell as indicated by the dashed box.
Here are two other options for accessing the Fill command:
Move the cursor to cell A2 and press [CTRL][CLICK] (only two keystrokes!).
Right-click in cell A2, [CTRL][MENU]→Fill.
Press the
key repeatedly to expand the dashed box to the desired row and press [ENTER].
Repeat Steps 3 and 4 for cell B2.
Here, the Fill command is used to copy my formulas to row 10.
Notice that the value of the account in column B is higher than the account value in column A. Of course, you'd probably like to find out when the first investment scenario exceeds the second.
To use Fill on both columns simultaneously, move to cell A10, press and hold the [SHIFT] key, and press the
key once to highlight cells A10 and B10. Now access the Fill command as before and copy both formulas to several more rows. Scroll down to see that the 5% investment strategy surpasses the other investment strategy in row 28!
The Fill Command can also be used horizontally to fill in a row of values.
