That would be incorrect use of an autonumber field.
Autonumber fields should never be seen or used for any meaningful data.
Their sole purpose is for surrogate primary keys and as a value to assign to
child records as a foreign key. The value of any field, variable, or
control can be presented with leading zeros using the Format function.
Additionally, you cannot expect a continuous unbroken sequence of numbers
with an autonumber field. There will be gaps caused by a user beginning a
record, but canceling or undoing the record before it is actually written to
the table. The number is assigned as soon as the first character is typed
into the first control on a form and whether the record is saved or not, the
number is consumed and will not be reused.
Please explain what you are wanting to do and perhaps we can help with the
how to do it.