NumberForm

NumberForm[expr,n]

prints with approximate real numbers in expr given to n‐digit precision.

NumberForm[expr,{n,f}]

prints with approximate real numbers having n digits, with f digits to the right of the decimal point.

NumberForm[expr]

prints using the default options of NumberForm.

Details and Options

NumberForm works on integers as well as approximate real numbers.
The following options can be given:

DefaultPrintPrecision	Automatic	default print digits for machine numbers
DigitBlock	Infinity	number of digits between breaks
ExponentFunction	Automatic	function to apply to exponents
ExponentStep	1	steps by which exponents can increase
NumberFormat	Automatic	function used to assemble the mantissa, base, and exponent
NumberMultiplier	"×"	string to use to indicate multiplication
NumberPadding	{"","0"}	strings to use for left and right padding
NumberPoint	"."	decimal point string
NumberSeparator	{",", " "}	string to insert at breaks between blocks
NumberSigns	{"-",""}	strings to use for signs of negative and positive numbers
ScientificNotationThreshold	{-5,6}	where to begin using scientific notation
SignPadding	False	whether to insert padding after the sign

All options except ExponentFunction and ExponentStep apply to integers as well as approximate real numbers.
You can mix NumberForm and BaseForm. »
The typeset form of NumberForm[expr] is interpreted the same as expr when used in input. »
When an input evaluates to NumberForm[expr], NumberForm does not appear in the output. »

Examples

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Basic Examples (2)

Display the first 10 digits of a numeric approximation to :

Display a number with 3 precise digits and 4 digits to the right of the decimal:

Scope (6)

The default display for a machine number:

Display more digits than the default:

Display fewer digits:

Format a complex number:

Format a high-precision number:

Change the display of numbers in a vector:

A matrix:

Change the display of inexact numbers in a mixed expression:

This number renders in a notebook with two digits of precision:

Force the number to be rendered with default options:

Options (13)

DefaultPrintPrecision (1)

By default, machine real numbers are typeset with 6 digits of precision:

Increase to 8 digits:

DigitBlock (2)

A default integer:

Digits separated in blocks of length 3:

Use five‐digit blocks with spaces as separators:

ExponentFunction (1)

Compute approximate powers of :

Restrict exponents to multiples of 3:

Include exponents only for powers greater than 10:

ExponentStep (1)

Default formatting to 10 digits:

Restrict exponent to multiples of 6:

NumberFormat (1)

Display numbers in a Fortran‐like form:

Display only the mantissas:

Display the exponents after converting to scientific form:

NumberMultiplier (1)

Use the default multiplier ×:

Use an asterisk (*) instead:

NumberPadding (1)

The default does not pad on the left or right:

Pad with spaces on the left:

Pad with 0s on the right:

NumberPoint (1)

The default is a period:

Display with a comma (,) instead:

NumberSeparator (1)

The default separator is a comma (,):

Use spaces instead:

NumberSigns (1)

The default includes negative signs but not positive signs:

Include positive signs as well:

Use words instead of symbols:

ScientificNotationThreshold (1)

By default, real numbers between 10^-5 and 10⁶ in absolute value are printed in decimal form, and in scientific form otherwise:

Change the transition thresholds:

SignPadding (1)

The default pads before signs:

Pad between signs and numbers instead:

Applications (1)

Display numeric approximations of with increasing precision and number of decimal digits:

Display in a tabular form:

Properties & Relations (5)

NumberForm and PaddedForm use the same mantissas and exponents by default:

ScientificForm has a single digit to the left of the decimal:

EngineeringForm uses exponents that are multiples of 3:

AccountingForm does not have exponents:

Convert a number to base 2:

Represent the number precise to 3 decimal digits in base 2:

Reconstruct the base 10 number precise to 3 digits:

Affect the display of numbers in MatrixForm or TableForm:

The typeset form of NumberForm[expr,n] is interpreted the same as expr when used in input:

Copy the output and paste it into an input cell. The 1.2 is interpreted as 1.23:

When an input evaluates to NumberForm[expr,n], NumberForm does not appear in the output:

Out is assigned the value 1.23, not NumberForm[1.23,2]:

Possible Issues (2)

Placeholder zeros may be needed if the requested precision is small:

Even when an output omits NumberForm from the top level, it is not stripped from subexpressions:

The output does not have NumberForm in it:

However, the variable e does have NumberForm in it, which may affect subsequent evaluations:

The product is not evaluated due to the intervening NumberForm:

Assign variables first and then apply NumberForm to the result to maintain computability:

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