This approximate number is displayed by default in scientific notation:

Show it in decimal form:

Show all 9 digits:

Display a small length in decimal form:

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:

Use fewer digits:

Change the display of numbers in a vector:

A matrix:

Change the display of inexact numbers in a mixed expression:

Like DecimalForm, AccountingForm does not use scientific notation:

They differ in other aspects, like the representation of negative numbers:

NumberForm and PaddedForm have exponents for powers greater than 5:

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

EngineeringForm uses exponents that are multiples of 3:

DecimalForm is effectively equivalent to NumberForm deactivating the option ExponentFunction:

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

Copy the output and paste it into an input cell. The 1000000. is interpreted as 1.`*^6:

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

Out is assigned the value 1.`*^6, not DecimalForm[10.^6]:

Zeros will be added to the left of the decimal point for large numbers with few digits in input:

If the input precision is too small, a message will be issued:

The same message will be issued if few significant digits are requested:

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

The output does not have DecimalForm in it:

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

The product is not evaluated due to the intervening DecimalForm:

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