Expand a number into a list of multiples of powers of 10:

Expand a number in base 2:

Specify the length of the output:

Expand an integer into a list of multiples of powers of 10:

Expand a rational number in base 2, obtaining a rational remaining part:

Expand a machine-precision real number, obtaining a machine-precision remaining part:

Expand an exact complex number in base 7:

Expand an inexact complex number in base 10:

Expand a negative integer:

Expand a real number in a rational base:

Expand a number using a machine-precision base:

Expand a rational number in a real base:

Expand a real number in a real base:

For an integer, when the length of the output is required to be larger than needed, NumberExpand pads with 0s on the right:

For a rational number with a finite-length decimal part, when the length of the output is required to be larger than needed, NumberExpand pads with 0s on the right:

For a rational number with an infinite-length decimal part, the last element of the output list is always nonzero:

For any number n, Total[NumberExpand[n,…]] equals n:

The total of the expansion of an exact number in an integer base is the number itself:

If the base is non-exact, the total will have a different precision:

For an exact number expanded into inexact parts, the difference with the total is smaller than the last part of the expansion:

Then Rationalize may be able to recover the original exact number:

When a non-exact number is expanded in an exact base, all the elements of the output list but the last are exact:

The last element is not necessarily zero:

For non-exact numbers, NumberExpand returns a list of parts corresponding to the digits of RealDigits:

Small variations of the input may result in representations containing multiple 9s:

The precision of Total[NumberExpand[…]] is effectively determined by the minimum precision of the input arguments:

NumberExpand automatically threads over lists:

Parts of the expansion unknown at the available precision are filled in as Indeterminate:

In this situation, the original number cannot be reconstructed: