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How to Spot a Numeral Zero from a Character O?

Monday, April 2nd, 2012 by | Filed Under: Computer Terms

Gloria writes:

Is there a way to distinguish between a zero and an “O” when entering a serial number? Sometimes – for various reasons – you receive a serial number that needs to be entered somewhere else, and I can’t tell the difference.

Many of us are confused by the shape of the numeral 0 and the capital ‘o’. If the text is digital, it is easier to identify by changing the font to one that distinctly differentiates between a zero and an ‘O’. However, distinguishing one from the other in printed copies, like serial numbers, is hard at times.

Some History

Most of the time, a check still gets cleared if you type it for $5 followed by two O’s and not zeros, but for those that care, let’s go back in history a bit. The situation used to be much different, once upon a time, when the closest thing we had to a computer was a typewriter. You’d be surprised to know that in the early days, typewriters made no distinction between a zero and an O – so much so, that some typewriters did not even have a separate key for zero.

Modern displays

With the advent of character displays, there came a need to distinguish the two. After all, it was all about typeface, and people love a good font. The digit zero has changed in form twice, once being represented with a slash and another time with a dot in between. However, none of these display styles for zero could strip it of its glory in the battle against ‘O’. So, in modern times, both zero and O have no dot or slash in them. The only thing that has changed is that a computer will not accept an O for a zero!

Distinguishing a zero from an O

The only probable way to distinguish between a zero and an O is to improvise. Most (but not all) fonts try to portray a zero as an oval with a sharp top and bottom and flat sides. If you turn a printed zero sideways, you will clearly see it resting on a flat belly. An O on the other hand, can be perceived as something that is easy to roll.

Here is a list of fonts and how they show a zero an O. As we can see, distinguishing a zero from an O within the same font is easy, but for some fonts, like Georgia, it gets a bit harder. Always remember, a zero will have nearly flat sides and an O will have a broadly rounded top and bottom in most cases.

Zero/o in caps Font Name
0/O  Arial
0/O  Andale Mono
0/O  Georgia
0/O  Book Antiqua
0/O  Times New Roman
0/O   Verdana

~Chinmoy Kanjilal


6 Responses to “How to Spot a Numeral Zero from a Character O?”

  1. Diane Mayotte says:

    Wonderful tip! Very informative. Thanks

  2. Walt Hammers says:

    A solid, very practical tip! The samples were very interesting.

  3. RB says:

    Ohhhhhh, thanks.

  4. Bob Smith says:

    Some folks might like to know that the zero of long ago can be add to many documents by pressing the Alt key, while typing on the numerical keyboard 0216 I’ve used this many times when talking to some of my ham radio buds and need to type a call sign using the zero. For instance KØABC
    Bob Smith WB6ODR

  5. Duc says:

    Thank you for sharing ! It’s helpful.

  6. Darissa says:

    This was brilliant…Thank you for the time to post it…I got a security code and tried twice…after the 5th time I would’ve been locked out! Two of the symbols were hard to distinguish between the o and zero! You may have just saved me getting locked out of a very important file! Thanks Again!

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