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While this is not a technical question per se, I finally found something I have no idea and couldn't find any answer online:

How many Cambridge Z88s were made and/or sold?

As it's related, a sub-question would be How long was the Z88 in production?

Delivery started in Jun 1987 and lasted at least until late 1989, but when did production really stop?

After much searching through real paper, I found a September 1987 issue of the UK magazine Popular Computing Weekly mentioning a production capacity of 1000 units per week and an intention to double this 'soon' to 2000. The same issue also features a short article about a deal with SCI, a larger US manufacturing company, to set up production at their Scottish plant. Still no added up production numbers.

Another hint, I just noticed, that one of my Z88s carries a 'Made in Scotland by SCI UK LTD' sticker with a serial number of 007092:

enter image description here

So there were at least 7000 units produced in the SCI plant. Also, since the contract was mentioned in the September 1987 issue in future form, it may be safe to assume that Cambridge LTD manufactured Z88s in their own works for at least 6 months, adding another 6-10k units. So ~20k can be seen as the absolute lowest limit.

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    No idea either. I have proof for one right here in the drawer. – tofro Mar 18 '18 at 9:36
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    If anyone would know, Rakewell would. They've been supporting the Z88 since it came out. I bought Z88 accessories from them back in the day. – scruss Mar 18 '18 at 11:24
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    @Raffzahn If you know there's a 000698, odds are good indeed that they started at or near 000001 then :) – Jim MacKenzie Mar 20 '18 at 2:15
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    @traal Jup, known, except as of now, we only have an extreme small sample of less than 10 while at the same time the upper known number is rather high in comparsion. So we need to shoot a few more Z88 to get their numbers :)) With that formula, the actual sample comes down to ~67500 Units - with a variance allowing an upper end in the millions. So again, lets shoot more. – Raffzahn Mar 20 '18 at 3:39
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    Thanks for reminding me of my Z88 - It received an internal ROM and RAM upgrade to 512 kBytes each today ;) (Had to rip the serial number, though, as one of the screws hides under it) – tofro Mar 20 '18 at 21:27
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I know it's bad style to answer ones own question. Still,I feel the need to publish my findings (*1):

Over the last 3 18 months, I've been able to collect serial numbers of 38 different Z88s, with 62271 being the largest.

Using the so called German Tank Formula, as traal suggested, yields 63909 as a result. So it might be safe to assume that there were less than 100,000 units, possibly even considerable less than 70,000. Unless there's some hidden stash with high serial numbers, that is.

As with many statistical methods there are other approaches and concerns, but Michael Steil has already used it twice to generate rather believable numbers for the C64 as well as for the Xbox, While others made a believable case for iPhones. So I'm inclined to go with it.

Fun part: As so often, the comments of anything about the C64 does carry the outcry of the fanboys. This time it's 'nananana ... statistics are neat but I know better and it's <beloved-fantasy-number>'

*1 - Beside, no-one has provided any answer so far.

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    Agreed to the fun part, to the extent that I wish I could give you a second +1 for it; my favourite was "it’s not the best research if you don’t know how to get to those numbers". So we've all been wrong about research all this time: the "best research" is starting from a conclusion and finding a way to get to it! – Tommy Jun 20 '18 at 15:17
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    Not sure it's bad style to answer one's own question; that's encouraged practise here on SE. – Wilson Jun 21 '18 at 7:47
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    Suggest you read retrocomputing.stackexchange.com/help/self-answer, this is explicitly encouraged across the entire SE network. If you think differently, you should probably work with meta to get the suggestion changed, but I don't think you'll have much luck since it's a great way to get more knowledge on to the sites. – user6464 Nov 23 '18 at 1:11
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    @paxdiablo Beside that it might be a good idea to abstain from a patronizing tone, even more so it is of no good to spread out a discusion from it's original location. I feel it might not only be a good idea, but quite useful to read prior comments before commenting. Wilson has exactly pointed out the same and I already did make my point clear. Reading helps to avoide superfluous drivel. – Raffzahn Nov 23 '18 at 1:23
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    Self-answering is a good thing if you find an answer yourself finally, especially if no-one else found one, and even if it's not 100%. Most professional questioners will go on with their research after posting their question, and I presume we here are such. I think it's better to have a self-given answer than none. But, Raffzahn, which reasons do you have? – the busybee Oct 26 at 9:47

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