Little research among HP-35 owners :-)


There are many very different opinions about the total number of HP 35 version 1 ("Red Dots") ever produced. A rough estimate could be made from serial numbers. HP 35 calculators have serial numbers 1143A XXXXX, with a few exceptions. AFAIK the lowest S/N of still existing HP 35 calculator is 1143A 00007. More interesting would be both the information about the highest known S/N version 1 and the information about the lowest S/N of HP 35 version 2. I know about a version 1 with the S/N 1143A 0324X. If you would be interested in this topic, you could take part in a little research. If you have HP 35 version 1 with a high S/N or HP 35 version 2 with a low S/N, post it here so we could roughly estimate the threshold S/N between HP 35 version 1 and HP 35 version 2


I think there were about 20000 red dots made - I have a 27000 V2 and am pretty sure to have seen a 22000 pictured as well...


I know about a version 1 with the S/N 1143A 0324X

You now know about two red dots from the very same batch... ;-)



Maybe it was just your HP 35 :-) I have seen that image on the net. I have found another red dot with a higher S/N 1143A 3770. Among many red dot's I've seen in real or pictured there was no one with a higher S/N than 03XXX. Frank writes in a previous message he is sure he have seen an image of one with S/N 22000. It would be interesting to find some existing versions 1 or versions 2 below/above S/N 20000 to confirm/refute the 20000 threshold assumption.


Maybe it was just your HP 35 :-) I have seen that image on the net
Oh, what a pity! I thought I found a brother in arms...:-)

Yes, that's probably mine: I thought I deleted the last two digits from the serial number, but it's actually one.

I have found another red dot with a higher S/N 1143A 3770

That's Gianmaria's one.

Let's hope someone else will post his/her findings.


I meant a V2 with ser.# 22000...


After an investigation I have found references to 2-4 still existing HP 35 Red Dot calculators in every thousand of serial numbers. But no Red Dot was found from 03770 up. I have found various references on the web, but the total number of known Red Dots I've found is only 14. Therefore there are too few data for an accurate statement, but a question arises whether the total number of ever produced HP 35 Red Dot could be higher than 4000. There are even a few HP 35's, which have Red Dot S/N, but in fact are versions 2 or higher. IMO those calculators changed from Red Dot to version 2 during some service repair. Another interesting fact is that among still existing Red Dots many have not the 2.02 ln e^x bug. More data would be appreciated, but due to the rareness of the version 1 it's a very difficult task.


I have an early version 2. It has the ROM bug, and a bump on the 5 key. Its serial number is 1143A40825.

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