# Introduction

When Charles Lamb wasn’t writing literary classics, he labored as an accountant for the East India Company. During his dual career —1791 to 1825— he often expressed a dim view of the business of business as it was when the standard calculating equipment consisted of a high stool, desk, quill pen, and a human brain—“I had perpetually a dread of some crisis to which I should be found unequal . . . I served over again all night in my sleep, and would awake with terrors of imaginary false entries, errors in my accounts, and the like . . .
There is little doubt that Lamb’s frustration with the burdens of his work sparked his creative genius-had he been content he might never have written anything of lasting significance. (In fact, his retirement from the East India Company marked the end of his productive period as a writer.)
At the risk of depriving the world of another businessman-cumartist, we have produced a device that takes the drudgery out of complex financial and business calculations—and makes them more accurate, too. The tool is the HP-80 electronic answer-machine that weighs only nine ounces (you can take it anywhere you go—and should), and replaces stacks of tricky tables and other such “inundata”. It is the first pocket calculator to offer built-in logic for solving business-oriented problems. There is no comparable tool available today!
To give you a sample of what you can do with the HP-80, switch the calculator to ON and we’ll work a typical compound interest problem. Suppose you wanted to calculate the effective annual rate of return on an investment as a basis for evaluating various investment opportunities. If you could buy property today for \$10,000 and could expect to sell it in 7 years for \$15,000, what would be the annual rate of return on your original investment? To solve, simply enter the known values as follows:
Key in 7 (number of years) and press n (number of periods in terms of time), key in 10000 (initial investment) and press PV (present value), key in 15000 (amount to be returned) and press FV (future value), then press i (interest). Find your answer (annual rate of return) on the display: 5.96 %
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