sight-impaired," says Tom Mock, a
staff engineer with the Electronic
Industries Association (EIA) in
Washington, D.C.
"Input is verified by voice simu-
lation," explains Mock. For any
calculator user, however, the voice
verification of what is entered can
improve accuracy.
There are three general classifi-
cations of hand-held calculators:
four- to six-function, prepro-
grammed, and programmable.
Your first step in choosing a calcu-
lator is to determine which of the
three best suits your needs.
Q Four- to six-function units.
They perform addition, subtrac-
tion, multiplication, division, and
one or two other functions, such as
percentages and square roots. They
include keys for adding or subtract-
ing to memory, memory recall, and
memory clear.
For basic math, this is probably
all the calculating power you will
need. You'll find this type of unit
useful in figuring taxes, balancing a
checkbook, and keeping track of
budgets.

Technological
advances mean
a lot more
power in the palm
of your hand.
puting angles, degrees, and other
math-oriented functions."
In business applications, prepro-
grammed units are especially useful
for figuring present and future
value, monthly payments on annu-
ities, bond yield, and loan amorti-
zation. The alternative is to use a
complicated book of interest tables,
in which case a calculator is still
needed for multiplying table values.
Units designed to calculate interest
usually include a feature for count-
ing the number of days between two
dates (also useful
for figuring such
things as the num-
ber of days until
midterm exams,
homecoming
weekend, etc.).
.' a Q Programmable
units.
While they of-
fer many of the
same features as
the other types of
units, they also of-
fer a computerlike
programming ca-
pacity that allows
you to tailor the calculator to your
own applications.
For instance, let's say that you
have a particular calculation that
you'll need to repeat many times-
such as separating loan payments
into interest and principal or figur-
ing sales tax on individual items.
First you must break down the cal-
culation into its steps, then enter the
computational routine into the cal-

culator's memory (usually by de-
pressing the "Learn" key). Once
this is done, you can execute the se-
quence with one keystroke when-
ever you need to.
Some specialized calculators can
be used to produce graphic dis-
plays. With automatic scaling rou-
tines, optimum screen usage is fully
automated in these systems. Some
versions of this type of calculator
are programmable, so that you can
create your own graphics. With
plug-in devices, a hand-held calcu-
lator can give you graphic capability
not available on many computer
systems.
Shopping skills
The type of calculator you buy
should be determined by your
computational needs. With all the
new models on the market, how do
you determine the one that's right
for you? Begin by shopping
around. Find out what features are
available and decide which ones you
should have. Don't be sold on "ex-
tras" you'll never use. On the other
hand, keep in mind that you don't
want to "outgrow" your calculator
right away.
Some questions to ask before you
buy:
" Is the calculator for personal or
academic use? If academic, how
advanced is your coursework?
" Will you need statistical or high-
math functions?
" How much can you afford to
spend?
" Is programming a feature you'll
need?
o'Where will you use the calcula-
tor? (For outdoor use, says
Mock, you'll want a liquid crys-
tal display; in dim light condi-
tions, you'll need LED display.)
The latest generation of calcula-
tors offers a wide range of choices.
Whether your needs stop with math
basics or have progressed to trig
functions, compucer conversions,
loan amortizations, and more,
there's a calculator that's just the
right tool for you. 40

I

D Preprogrammed units.
These units have been pro-
grammed to perform specific func-
tions according to their primary ap-
plication. Mock explains: "Statisti-
cal units are useful to students in-
volved in a lot of number crunch-
ing. Business units are prepro-
grammed for real estate loan cal-
culations or banking. And engi-
neering units are designed for com-

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