Casio fx-115s- User Manual

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A true calculator

Harold Thimbleby

Swansea University Department of Computer Science

Existing calculators are unreliable and difficult to use, and they are

marketed misleadingly. A new calculator is described that is simple,

reliable and very powerful.

Originally published in

Engineering Science and Education Journal

,

6

(3):128–136, 1997.

This paper provides a selection of worked examples for the n e w

calculator: including working out the radius of a sphere of given weight; a

financial calculation, recreational mathematics (Ramanujan’s 1729

problem), and using the built-in tables of interesting number facts.

C

ALCULATORS

are used in all aspects of work, from laboratories to banks, as

well as in everyday life, from paying loans to passing exams. Handheld

electronic calculators seem impressive, and they have been around long

enough for us to take them for granted. They are ubiquitous: they can be

found in wrist watches or in rulers; they may be credit-card sized, pocket

sized, or ‘desk top’ with their own printer. Calculators are required in school

curriculums, and no office would be complete without one. They are

probably the most commonly used and experienced of all modern

‘information technology’ electronic gadgets.

Calculators are also at the centre of controversy. Our children are not

good at mathematics, and calculators get some of the blame. Is this because

calculators stop children thinking about numbers, so they never learn any

insight into mathematics?

This article suggests that things are worse: the maths that calculators do is

damaged, and learning to use a calculator is really more about learning to

cope with unnecessarily bad technology than about learning about numbers.

The first article on the front page article of

The Times

(December 7, 1995)

entitled, “Calculators banned in exams after maths standards fall,” claimed

that School Curriculum and Assessment Authority officials were worried

about childrens’ falling standards in decimal places, fractions and “lack of

basic understanding of percentage.” Ironically these problems children have

with maths are identical to problems calculators themselves have, as we shall

see. Maybe the problems are not calculators

per se

, but with the way they are

conventionally designed? This article will not only criticise current calculators,

but suggest a workable alternative.

Background

After the abacus, more-or-less unchanged through antiquity, the first main

development in devices for making calculation easier was John Napier’s

invention of logarithms around 1594. (He was also one of the first people to

make systematic use of the decimal point.) Napier later published a book,