HP 10413 Datasheet download pdf (Page 40)

Earlier we examined the use of the MODES view, and the meaning of Number

Format. We discussed the use of the settings Fixed, Scientific and

Engineering, but left the setting of Fraction for later. The Fraction

setting can be a little deceptive.

Most calculators have a fraction key, often labeled

, that allows you to

input, for example,

as 123¬¬ or something similar. What these

calculators usually won’t do is allow you to mix fractions and decimals.

On most calculators

137

+⋅

will give a decimal result - the calculator will

not attempt to convert the

37⋅ into a fraction. The reason for this is that

while some decimals like 0.25 are easy to convert to a fraction, others, such

as recurring ones, are not so easy. Most calculators opt for the easy option

of switching to a decimal answer in any mixture of fractions and decimals.

The makers of the hp 39g+ took a very different approach. Once you select

Fraction mode, all numbers become fractions - including any decimals.

The first point to remember is that there is no

provision for inputting mixed fractions such as

. Fractions are entered using the divide

key and, while the calculator is quite happy

with improper fractions such as 5/3, it

correctly interprets 1/2/3 as one half divided by 3 and gives a result of 1/6

. The solution to this is simply to enter mixed fractions as (1+2/3).

Calculator Tip

You need to be careful with brackets or “order of

operations” problems may occur, such as

being

interpreted as 1+(2/3*1/5) rather than as it should be:

(1+2/3)*1/5. When in doubt, use brackets for mixed

fractions.

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HP 10413 Datasheet Page 40