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A number may be written in binary, octal, decimal, or hexadecimal by the
use of a radix prefix. The radix prefixes are `#b`

(binary),
`#o`

(octal), `#d`

(decimal), and `#x`

(hexadecimal).
With no radix prefix, a number is assumed to be expressed in
decimal.

A numerical constant may be specified to be either exact or inexact by a
prefix. The prefixes are `#e`

for exact, and `#i`

for
inexact. An exactness prefix may appear before or after any radix
prefix that is used. If the written representation of a number has no
exactness prefix, the constant may be either inexact or exact. It is
inexact if it contains a decimal point, an exponent, or a `#`

character in the place of a digit, otherwise it is exact.

In systems with inexact numbers of varying precisions it may be useful
to specify the precision of a constant. For this purpose, numerical
constants may be written with an *exponent marker* that indicates
the desired precision of the inexact representation. The letters
`s`

, `f`

, `d`

, and `l`

specify the use of
*short*, *single*, *double*, and *long* precision,
respectively. (When fewer than four internal inexact representations
exist, the four size specifications are mapped onto those available.
For example, an implementation with two internal representations may map
short and single together and long and double together.) In addition,
the exponent marker `e`

specifies the default precision for the
implementation. The default precision has at least as much precision as
*double*, but implementations may wish to allow this default to be
set by the user.

3.14159265358979F0 Round to single — 3.141593 0.6L0 Extend to long — .600000000000000

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