.\" $OpenBSD: arithmetic.6,v 1.12 2015/09/12 16:10:25 schwarze Exp $
.\"
.\" Copyright (c) 1989, 1993
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.\" This code is derived from software contributed to Berkeley by
.\" Eamonn McManus of Trinity College Dublin.
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" @(#)arithmetic.6 8.1 (Berkeley) 5/31/93
.\"
.Dd $Mdocdate: September 12 2015 $
.Dt ARITHMETIC 6
.Os
.Sh NAME
.Nm arithmetic
.Nd quiz on simple arithmetic
.Sh SYNOPSIS
.Nm arithmetic
.Op Fl o Cm +\-x/
.Op Fl r Ar range
.Sh DESCRIPTION
.Nm
asks you to solve problems in simple arithmetic.
Each question must be answered correctly before going on to the next.
After every 20 problems, it prints the score so far and the time taken.
You can quit at any time by typing the interrupt or end-of-file character.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl o Cm +\-x/
By default,
.Nm
asks questions on addition of numbers from 0 to 10, and corresponding
subtraction.
By supplying one or more of the characters
.Cm +\-x/ ,
you can ask for problems in addition, subtraction, multiplication, and
division, respectively.
If you give one of these characters more than once, that kind of problem
will be asked correspondingly more often.
.It Fl r Ar range
If a
.Ar range
is supplied,
.Nm
selects the numbers in its problems in the following way.
For addition and multiplication, the numbers to be added or multiplied
are between 0 and
.Ar range ,
inclusive.
For subtraction and division, both the required result and the number to
divide by or subtract will be between 0 and
.Ar range .
(Of course,
.Nm
will not ask you to divide by 0.)
The default
.Ar range
is 10.
.El
.Pp
When you get a problem wrong,
.Nm
will remember the numbers involved, and will tend to select those numbers
more often than others, in problems of the same sort.
Eventually it will forgive and forget.
.Pp
.Nm
cannot be persuaded to tell you the right answer.
You must work it out for yourself.
.Sh DIAGNOSTICS
.Dq What?
if you get a question wrong.
.Dq Right!
if you get it right.
.Dq Please type a number.
if
.Nm
doesn't understand what you typed.
.Sh SEE ALSO
.Xr bc 1 ,
.Xr dc 1