Precisa 366-12


I received the machine from the original owner who bought it in 1968 and used it three years for his technical study.  Büromaschinen Lexicon  mentions this machine much later starting 1972.  Apart from basic functionality the machine allows the result of a calculation to be transferred to the multiplication register for continued multiplication. It also offers a way to copy the input register to the multiplication register, that way simplifying a square root calculation.

It is smaller and with 9 Kg lighter than many  of its competitors. Even an electronic calculator like the Philips P252 is almost twice as big and weighs about 15 Kg !

This particular machine did not show oil and grease all over the mechanism. That may explain why after almost 45 years it immediately worked well and seems to operate reliably.



As usual using the “+ D” and “-” keys.

The ‘R’ key used with the  “+ D” or “-” key repeats the addition or subtraction.


Enter 1st number,  push the ‘X’-button,  enter the 2nd number, then push one of the buttons below the ‘X’-button.

(‘<>=’ does not alter the result register, ‘*=’ clears it)


Enter the number,  then push the ‘R’ + the ‘X’ button. Next  push one of the buttons below the ‘X’-button.


Enter the  1st number,  then push the “+ D”-key,  next enter the 2nd number and then one of both ‘:“-keys.

 (‘:<>’ does not alter the result register, ‘*:*’ clears it)

Function of some keys, switches etc:

Calculator InfoRepair information & pictures of internals

Click to view a full size picture (opens in a new tab)

Video Assets: adverts, brochures, etc

Serial number:

Build in:


Rotation speed:


Production until:


D 146 823

Ca. 1968

Addition, Subtraction, Full automatic Multiplication,  Division and Square

220 RPM

1968 ? (See Details below)

1975 ?

DM 1580-  in 1972 (Source: Büromaschinen Lexikon)