The following problems are taken from the article "Mastering the Math Behind Your Money" in the May 1989 issue of Money magazine. The article provided keystrokes for the HP 12c calculator. The following keystrokes show the solutions for the same problems using the HP 10b. Please note that there are some calculations that will be slightly different due to rounding of some numbers on the part of the authors of the article.
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HP 10b Calculator  TVM Examples
Calculator symbol key
The procedures in this document use the following text to represent symbol keys:
Key

Description

Text Representation


colored key; shift key

SHIFT

I. How much should be saved?
Set to BEGIN mode. Press SHIFT, then BEG/END if annunciator is not displayed.
Keys

Display

Description

Press 1, SHIFT, then P/YR

1.00

Sets annual compounding

Press 2879, [+/], then PV

2,879.00

Stores today's money value

Press 7, then I/YR

7.00

Calculates future cost

Press 10, then N

10.00
 
Press 0, then PMT

0.00
 
Press FV

5,663.43
 
Press 12, SHIFT, then P/YR

12.00

Sets monthly compounding and payments

Press 0, then PV

0.00

Calculates monthly investment

Press 120, then N

120.00
 
Press 8.5, then I/YR

8.50
 
Press PMT

29.89

II. How big of a mortgage can be afforded?
Set to END mode. Press SHIFT, then BEG/END if BEGIN annunciator is displayed.
Keys

Display

Description

Press 12, SHIFT, then P/YR

12.00

Sets monthly payments

Press 360, then N

360.00

Stores known values

Press 1100, [+/], then PMT

1.100.00
 
Press 11, then I/YR

11.00
 
Press 0, then FV

0.00
 
Press PV

115,506.98

Calculates mortgage amount

note:
The difference in mortgage amount is because the article used a rounded figure for interest rate on the HP 12c.
III. What is really being earned on investments?
Set to END mode. Press SHIFT, then BEG/END if BEGIN annunciator is displayed.
Keys

Display

Description

Press 1, SHIFT, then P/YR

1.00

Sets annual payments

Press 5000, [+/], then PV

5,000.00

Stores known values

Press 8000, then FV

8,00
 
Press 3, then N

3.00
 
Press 0, then PMT

0.00
 
Press I/YR

16.96

Calculates annual return

The following routines give solutions to several problems mentioned in the body of the article. All solutions assume the calculator is set to END mode.
Press SHIFT, then BEG/END if BEGIN annunciator is displayed.
Home
What are the monthly payments on a loan?
Keys

Display

Description

Press 12, SHIFT, then P/YR

12.00

Sets monthly payments

Press 110000, then PV

110,000

Stores known values

Press 360, then N

360.00
 
Press 11, then I/YR

11.00
 
Press 0, then FV

0.00
 
Press PMT

1,047.56

Calculates monthly payment

Buying or leasing a car
The buy option:
Keys

Display

Description

Press 12, SHIFT, then P/YR

12.00

Sets monthly payments

Press 321, [+/],then PMT

321.00

Stores known values

Press 48, then N

48.00
 
Press 6, then I/YR

6.00
 
Press 0, then FV

0.00
 
Press PV

13,668.28

Calculates the price to buy

Discounting $5,000 over 4 years at 6 percent inflation:
Keys

Display

Description

Press 12, SHIFT, then P/YR

12.00

Sets monthly compounding

Press 48, then N

48.00

Stores known values

Press 6 then I/YR

6.00
 
Press 5000, then FV

5,000.00
 
Press 0, then PMT

0.00
 
Press PV

3,935.49

Calculates today's value of Projected resale

The lease option:
Keys

Display

Description

Press 12, SHIFT, then P/YR

12.00

Sets monthly payments

Press 48, then N

48.00

Stores known values

Press 6, then I/YR

6.00
 
Press 325, [+/], then PMT

325.00
 
Press 0, then FV

0.00
 
Press PV

13,838.60

Calculates the price to lease

Investments
What is the value of future income from annuity or other investments?
Keys

Display

Description

Press 12, SHIFT, then P/YR

12.00

Sets monthly payments

Press 2500, then PMT

2,500.00

Stores known values

Press 204, then N

204.00
 
Press 8, then I/YR

8.00
 
Press 0, then FV

0.00
 
Press PV

278,316,83

Calculates today's value of the future income

note:
The difference in the amount of today's value is due to the fact that the article used a rounded figure for interest.
What is the yield to maturity (of a bond)?
Keys

Display

Description

Press 1, SHIFT, then P/YR

1.00

Sets annual payments

Press 110, then PMT

110.00

Stores known values

Press16, then N

16.00
 
Press 900, [+/], then PV

900.00
 
Press 1000, then FV

1,000.00
 
Press I/YR

12.47

Calculates yield

What is the interestrate risk on a bond?
Keys

Display

Description

Press 1, SHIFT, then P/YR

1.00

Sets annual payments

Press 1000, then FV

1,000.00

Stores known values

Press 100, then PMT

100.00
 
Press 10, then N

10.00
 
Press 11, then I/YR

11.00
 
Press PV

941.11

Calculates the price

What if the rates drop to 9 percent?
Keys

Display

Description

Press 9, then I/YR

9.00

Stores new interest rate

Press PV

1,064.18

Calculates price

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