These two examples show how to create an Excel-like spreadsheet for creating sinking fund and amortization schedules using the TABLE facility of the graphing calculator.

Annuity: $100 per month into an account earning 9% compounded monthly.  Find the interest earned during each year.
 

The x-variable will stand for the year.  We will define three functions: Y1 = future value at end of current year Y2 = future value at end of previous year Y3 = interest = increase in future value - payments = Y1 - Y2 - 1200 For directions on defining functions, see the lesson on GRAPHING.  Opposite is the screen after defining Y1 and Y2. It reads as follows: Y1 = 100*(1.0075^(12*X)-1)/.0075 Y2 = 100*(1.0075^(12*(X-1))-1)/.0075
Now to define Y3.  Place the cursor at the definition point for Y3.  Now Y-VARS, 1 (to select Function), 1 (to select Y1), ENTER gives us:
Now finish the formula:
To see the "spreadsheet", press TABLE:
To see Y3, use the =>:
The Y3 column shows interest paid in each year.

Annuity: Amortize a $6000 debt at 12% compounded monthy over 3 years.  We use the Present Value formula (not shown) to compute the monthly payment = $199.29, or $2391.48 total payments per year.
 

As above, the x-variable will stand for the year.  We will define four functions: Y1 = present value at end of current year Y2 = present value at end of previous year Y3 = reduction in principal owed = Y1 - Y2 Y4= interest paid = payments - Y3
See above discussion for how to get Y-variables into the formulas. Opposite are the functions:
To see the "spreadsheet", press TABLE. Opposite are spreadsheet columns X (year), Y1 (current PV) and Y2 (previous PV).  Note: ignore the rows after 3, when the loan has been repaid.
Here are columns Y3 (reduction in amount owed) and Y4 (interest paid):
These columns tell us how each year's total payment of $2391.48 was divided up into: Y3 = reduction of loan Y4 = interest payment