arithmetic - provide drill in number facts
/usr/games/arithmetic [ +-x/ ] [ range ]
Arithmetic types out simple arithmetic problems, and waits for an answer to be typed in.
If the answer is correct, it types back "Right!", and a new problem. If the answer is
wrong, it replies "What?", and waits for another answer. Every twenty problems, it pub-
lishes statistics on correctness and the time required to answer.
To quit the program, type an interrupt (delete).
The first optional argument determines the kind of problem to be generated; +-x/ respec-
tively cause addition, subtraction, multiplication, and division problems to be generated.
One or more characters can be given; if more than one is given, the different types of
problems will be mixed in random order; default is +-
Range is a decimal number; all addends, subtrahends, differences, multiplicands, divisors,
and quotients will be less than or equal to the value of range. Default range is 10.
At the start, all numbers less than or equal to range are equally likely to appear. If
the respondent makes a mistake, the numbers in the problem which was missed become more
likely to reappear.
As a matter of educational philosophy, the program will not give correct answers, since
the learner should, in principle, be able to calculate them. Thus the program is intended
to provide drill for someone just past the first learning stage, not to teach number facts
de novo. For almost all users, the relevant statistic should be time per problem, not