Why do banknotes even need alpha prefixes?

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OK, I know I won't be popular with insert note collectors for suggesting this ...but why does the BofC continue using alphabetic prefixes before the sheet numbers?

Why don't they go back to what they did for the 1979 series and just use numbers?  Then you wouldn't need to know which prefix letters are used for each denomination.

Since the 1979 fivers had "3" as their prefix and the 20s had "5" as theirs, the $10 could use "4", the $50 could have "7" and the $100 could have "8".  "1" and "2" could be reserved in case the $1 and $2 notes are resurrected.  "6" could be reserved if the $25 note is ever resurrected and "9" could be kept for any future $1,000 notes.  As in 1979 the 2nd digit could denote the printing company and the rest would be the sheet number.

Just thinking of this from a business perspective...the current alphanumeric serial number system is unnecessarily complicated.  Even though I'm a collector, I can't be bothered memorizing which letters should apply to which denominations!

You can get alot more combinations by having letters.
26 x 26 x 26 x 10Million with letters (or something like that).

No letters, and you are capped at 0 to 9999999...999 or however high that number may be.


Secondly, I see no reason to point a change like this to impact insert collectors.  How about changeover collectors?  Most people are aware of the date on the bottom of the notes now, and the rarity of small ranges.
This would impact most everybody.

You can get alot more combinations by having letters.
26 x 26 x 26 x 10Million with letters (or something like that).

No letters, and you are capped at 0 to 9999999...999 or however high that number may be.


Secondly, I see no reason to point a change like this to impact insert collectors.  How about changeover collectors?  Most people are aware of the date on the bottom of the notes now, and the rarity of small ranges.
This would impact most everybody.

It's not quite 26^3 * 10,000,000 since they don't use every letter of the alphabet. 

I am not really satisfied with the answers here.  I don't know why they chose alpha prefixes to begin with and why they kept them.

I do know that one letter typically denotes the printer, (which could be done with numbers as well.)   I also know that the BofC did use number-only serial numbers in the 1979 $5 and $20.  There must be a reason why they decided not to continue using number-only serial numbers in the Bird Series.

Brad

AAA0000000 allows enough possibilities to uniquely identify a banknote from 1982 through somewhere around 2100, assuming we don't suddenly print a few billion notes.
00000000000 was fairly quickly reaching exhaustion, at least for the $20s. It would not have remained feasible for long.

Look at it this way... Since introducing the AAA system, the A-- prefixes are almost totally saturated, as are the E-- prefixes. Since its design, each printer was left with several overflow letters, namely B, C and presumably D for BABN, and F, G, H & J for CBN. CBN has been making use of F-- increasingly, but G-- and H-- have so far only been used for three series of $5 notes each. BABN has used a few series in B--, and just one in C--.

This all happened over a span of approximately 25 years. The two-letter prefixes of the 1954 series were completely exhausted within about 20 years, and the two-letter prefixes of the multicoloured series were nearly exhausted within 12 years, even considering that the 1979 $5s and $20s made an early exit from that program. If they would have reset the system instead of adding a letter, I predict that it would have been exhausted in less than 10 years, probably to around the time the Birds Series was introduced. If the Birds Series used two-letter prefixes, the system would have been exhausted with only the $2 and $5 notes, leaving no room for the other 5 denominations, especially the $20, which ate up ~10 series all on its own.

With the 11-digit serials, it is really a 4-digit prefix and a 7-digit serial. However, since the first digit represents the denomination, and the second represents the printer and/or test/replacement status, the options become limited to just a few  groups of 100 prefixes. The 1979 $20s used 50--, 51--, 52-- and 56-- in less than 15 years. If continued, I expect they would have been completely exhausted by now, if not a few years ago. The $5 notes used up half of 30-- and used 31-- and 33-- for replacements and tests. This was done in 7 years. When the Birds notes came out, and especially once the $2 was retired, the $5 note was printed in hoards. I'll leave it to you to figure out how fast they would have run out.

The point here is that AAA0000000 is 50 to 100 years more capacity than 00000000000.
(And if the BoC continues reusing prefixes such as ALA-ALZ, then it could go on indefinitely). <gripe>The system was perfect until they screwed around with repeating prefixes!</gripe>

The total number of possible combinations is somewhere between 22 *22*22 (if you exclude I, O, Q and X) =10648 and 25*25*25 = 15625 possible arrangements, depending if you put in use the I, O and X.  Many of these will never be used (just to think about a "SEX" prefix... ), as some were not used (that you can find by yourself).

Speaking about reusing old prefixes from defunct series, I cannot figure why the BoC had the need to reuse the old  and obsolete prefixes.  If they were running out of prefixes, I could have understood, but there is still plenty of unused prefixes, so where was the need? Once arrived to AZZ, why they hadn't step back to the denomination letter "I" and continue with BIA, BIB and so on?  These is something messy in the BoC... .

And incitentally, when the prefixes on the 20$ note will arrive to ALZ, what will be the next denominational letter?  Will the BoC unearth another old prefix?  the "R"? The "U"?, the "B"?  or resume with  the initial letter "I"?  We will know quite soon...