NAME

arithmetic − provide drill in number facts

USAGE

/usr/games/arithmetic [ +−x/ ] [ range ]

DESCRIPTION

Arithmetic presents simple arithmetic problems, and waits for you to type an answer.  If the answer is correct, it replies “Right!”, and supplies a new problem.  If the answer is wrong, it replies “What?”, until you respond correctly. 

The first optional argument determines the kind of problem to be generated. A plus sign (+), minus sign (−), lowercase x, and a slash (/) produce addition, subtraction, multiplication, and division problems respectively.  Specifying more than one of these characters on a command line generates a variety of problem types, all mixed in random order. Specifying any characters other than the four mentioned here also produces a random mix of problem types. If you specify no argument to arithmetic, subtraction problems appear by default. 

The second optional argument is range, a decimal number. If used, all addends, subtrahends, differences, multiplicands, divisors, and quotients will be less than or equal to this number. The 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. 

Every twenty problems, it publishes statistics on correctness and the time required to answer.  Specifically, the program tells you the number of correct and incorrect answers that you have given, as well as the total percentage of those correct. It also tells you how much time (in seconds) has elapsed, and the average number of seconds it took you to answer each problem. For example, the program may output something like this:
    Rights 20; Wrongs 1; Score 95%
    Total time 50 seconds; 2.5 seconds per problem

To quit the program, type an interrupt (↑Q). 

NOTES

As a matter of educational philosophy, arithmetic does not supply correct answers, since the learner should be able to calculate them. Thus, it does not try to teach number facts, but instead serves as a drill program for those just past the first learning stage of arithmetic. Usually, the most relevant statistic it provides is time per problem, not percent correct.