# Leading zero

A leading zero is any 0 digit that comes before the first nonzero digit in a number string in positional notation. For example, James Bond's famous identifier, 007, has two leading zeros. When leading zeros occupy the most significant digits of an integer, they could be left blank or omitted for the same numeric value. Therefore, the usual decimal notation of integers does not use leading zeros except for the zero itself, which would be denoted as an empty string otherwise. However, in decimal fractions strictly between −1 and 1, the leading zeros digits between the decimal point and the first nonzero digit are necessary for conveying the magnitude of a number and cannot be omitted, while trailing zeroes- zeroes occurring after the decimal point and after the last nonzero digit- can be omitted without changing the meaning.

Often, leading zeros are found on non-electronic digital displays or on such electronic ones as seven-segment displays, that contain fixed sets of digits. These devices include manual counters, stopwatches,odometers, and digital clocks. 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 to make names of the equal length.

Leading zeros also present whenever the number of digits is technically fixed (such as in a memory register), but the stored value is not large enough to result in a non-zero most significant digit. The count leading zeros operation efficiently determines the number of leading zero bits in a machine word.

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