arithmetic.6

unix v7是最后一个广泛发布的研究型UNIX版本

.TH ARITHMETIC 6 
.SH NAME
arithmetic \- provide drill in number facts
.SH SYNOPSIS
.B /usr/games/arithmetic
[
.B +\-x/
] [ range ]
.SH DESCRIPTION
.I 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 publishes
statistics on correctness and the time required
to answer.
.PP
To quit the program,
type an interrupt (delete).
.PP
The first optional argument determines the kind of problem
to be generated;
.B +\-x/
respectively 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
.B +\-
.PP
.I Range
is a decimal number;
all addends, subtrahends, differences, multiplicands, divisors,
and quotients will be less than or equal to the value of
.IR range .
Default
.I range
is 10.
.PP
At the start, all numbers less than or equal to
.I 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.
.PP
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
.I de
.IR novo .
For almost all users,
the relevant statistic should be
time per problem, not percent correct.