Not to be confused with zero leading, a leading zero is the number zero that precedes a string of other numbers.
- Under some circumstances the leading zero may be dropped:
A London phone number reaches the same place whether it is written as 020 7111 2222 or 20 7111 2222 as long as your audience knows that from outside the country you don't dial the leading zero.
- In other cases you would never drop the leading zero:
James Bond 7? I don't think so.
Uniformity and Alphabetization
Sometimes the leading zero is used to give numbers the same length for a neater appearance whether it's a column of numbers or a series of file names with numbers.
01.03
10.25
00.15
file001.doc
file021.doc
file223.doc
A leading zero can also help with alphabetical lists that contain numbers:
Without leading zero:
Task 1
Task 10
Task 2
With leading zero*:
Task 01
Task 02
... (03 thru 09)
Task 10
* If you had items in the hundreds you'd start with 001, 002, etc. and if you had thousands you'd start with 0001.
Using Leading Zeroes
Before deciding to drop a leading zero (or add one), make sure that it doesn't alter the meaning or intent of the numbers. For example, 7, 07, and 007 can be distinctly different numbers depending on the context.In writing numbers with decimals, especially within a block of text, including a leading zero — 0.15 instead of just .15 — can be helpful because that tiny dot of a decimal may be overlooked otherwise. However, consult any style guide in use because some may require a leading zero and others may discourage its use.
Be consistent. If you are going to write dates with a leading zero, such as 02 JUN 2013 or 11/04/58 then use a leading zero on all dates from 01 to 09.
Some uses of leading zeroes in programming, HTML, file naming, and phone numbers:
- Number Bases and Leading Zeroes in JavaScript
- How to Add Leading Zeroes to a Number in Delphi Format
- CSS List Styles (including for leading zero numbered lists)
- Rename a Series of Files With IrfanView | ACDSee | XnView Image Viewer
- See the comments under Phone Numbers: Dots or Dashes for some discussions of writing phone numbers with and without a leading zero.
