Leading zero(es):

A zero that appears in the leftmost digit(s) of a number. Many programs that display numbers in columns allow you to specify whether the number should be preceded with spaces or leading zeros, as shown below.

leading zeros - spaces
0003.45 - 3.45
0148.70 - 148.70

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ref. http://www.webopedia.com/TERM/L/leading_zero.html

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Note added at 2005-07-11 13:45:20 (GMT)
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From wikipedia:

A leading zero is any zero that proceeds a number string beginning with a non-null value. Often, leading zeros are found on non-electronic and LED digital displays that contain fixed sets of digits, such as the manual counter, the stopwatch, the odometer and the digital clock. Leading zeros are also generated by many older computer programs when creating values to assign to new records, accounts and other files, and as such are likely to be used by utility billing systems, human resources information systems and government databases. Many digital cameras and other electronic media recording devices use leading zeros when creating and saving new files.

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Note added at 2005-07-11 13:45:34 (GMT)
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Or \"prefix zero\"

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* BIN$(x[,y]) zet een long integer om in een binaire string die de waarde van X weergeeft. Als de optionele Format parameter wordt meegegeven, dan zal een string van Y characters (maximaal 32) worden aangemaakt, gevuld met voorloopnullen. Als Y nul is of niet aanwezig is, wordt het aantal benodigde characters voor nauwkeurige weergave van het getal opgegeven.

AND

* HEX$(x[,y]) function converts a long integer to a hexadecimal string representation of the value of x. If the optional format parameter y is included, then a string of y digits (up to a maximum of eight) is returned, filled with leading zeros. If y is zero or missing, the returned string has the number of digits necessary to accurately represent the number.

ref. http://www.panthouse.tmfweb.nl/pb/versie5-6.htm

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Note added at 2005-07-11 13:47:58 (GMT)
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Or \"zeros\"