About me

My name is Kees Nagtegaal (1949) and I live in the Netherlands.

I studied mathematics at Leiden University and I was a math teacher (1970-2011) on a highschool (HAVO and VWO). Now I am retired.

In my opinion, this profession is for me the link to the calculators.

My Collection

I have a collection of non-electric calculators, adding machines, counters, slide-rules and abaci.


Slide-rules are not important to me, that's why many of them are for sale. The right stuff for my collection are the addiators and other small adders (slide-adders, chain-adders, etc). 

My first calculator

I found my first calculator in 1999. It is an Original Odhner 24. I saw it in Amsterdam in an antiques and collectable shop. This Odhner was the start of my calculator-collection (or calculator-obsession).

I am member of......

I am member of  the Dutch Circle of Historical Calculating Instruments. This circle is an informal group of collectors of slide rules, ancient calculators or historical calculating instruments.



I am also member of I.F.H.B.:  Internationales Forum Historische Bürowelt. This (German) circle is a group of collectors of ancient calculators and historical typewriters.