why we write in short S.No for serial number where as ther is no " o" in Number ?

Answer 1

"no." is not based on the English word "number." It means 'number', but like many of our abbreviations (such as etc., i.e., e.g., viz.) it is based on a LATIN word.

The basic form of the word in Latin is "numerus". "Numero" is the "ablative case" form. The ablative form was used here because that fit the usage English writers needed when they introduced the form into English in the 17th century (in expressions of the sort "men, in number three").

Also note: the numero sign used to always use a RAISED (or "superscript") O. (Typewriters could not handle this very well, unless you wanted to manually move the carriage up and down. But wordprocessing, personal computing make it much easier.)
http://en.wikipedia.org/wiki/Numero_sign

This use of a superscript at the end is another indicator that it is the letter stands for the case ENDING, rather than, say, the second letter of the word. (The practice of abbreviating a word by its first letter or two plus the case ending is ancient. For example, in the early church --by the 2nd century-- copies of the Greek New Testament would abbreviate the divine names by using the first letter or two followed by the case ending, with a line over the whole to mark it as an abbreviation.)
http://www.skypoint.com/~waltzmn/NominaSacra.html

Answer 2

Abbreviation For Serial Number

Answer 3

Serial Number Abbreviation

Answer 4

It's a very interesting question, looking forward to reading the answers

Answer 5

in Middle Times number was written as "nombre".....thts why the symbol No. is used...

Answer 6

Wanted to ask this question too this morning

Answer 7

The same question shows up again