The MADAS 20ATG is a very  luxury full function high-end mechanical calculator. There is an extra register in the carriage which offers the posibility to totalise results of individual multiplications.  This register can’t be brought back into the calculation process, so I wouldn’t consider it to be a real memory.  The counter register II is split in two parts.  It’s possible to clear only the left part and leave the current result in the right part.  Furthermore the machine is noticeable smaller than other machines.  The extra register, split register II and the many buttons and switches make it a versatile machine but this versatility comes at a price;  it’s difficult to operate.  It was also very expensive compared to competitors with equally versatile machines like the Friden SBT10, the Diehl DSR18 and Olympia RA20.



Enter a number and hit the “+” or the “-” key.


Enter the first number and hit the large bar.   Enter the second number and hit the bar again.  Multiplication is now executed.


Enter the first number and hit the “:” key.  Next enter the second number and push the “Div” key.  Input for a division is entered in the right part of the keyboard.  The result appears in the register II.

Function of some special keys, switches etc:

Calculator Info
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Serial number:

Build in:


Rotation speed:


Production until:



Ca. 1953

Addition, Subtraction, Fully automatic  Multiplication and  Fully automatic Division

Ca. 1953

Ca. 1960  (The almost identical 20BTG has been produced till ca. 1967 )

Ca. DM 5825 in 1959 (Bron: BüromaschinenLexikon)

Repair information & pictures of internals