Friden SBT10


The Friden SBT10 is a very  luxury full function mechanical calculator. It has functions which are available on very few machines like a result register that can be split into two parts where both parts support back transfer to the input register (keyboard). There is also the option to totalise results of a series of multiplications in the counter register.

Because of its versatility it’s not an easy machine to operate.



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


Enter the first number on the dedicated 10-digit keyboard.  Enter the second number on the main keyboard .  Multiplication is executed when the “MULT”, “ACCUM MULT” or “NEG MULT” are pushed.  


Enter the first number and hit the “DIVD” key.  Next enter the second number. When now both  “:” keys are pushed the division is executed. The result appears in the lower register.

Function of some special keys, switches etc:

Calculator Info
Friden SBT10 Friden SBT10 Friden SBT10
Friden SBT10 Friden SBT10

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Serial number:

Built in:


Rotation speed:


Production until:



Second half of 1960

Addition, Subtraction, Fully automatic  Multiplication and  Fully automatic Division


1965  (Büromaschinen Lexikon  still contains this calculator in the1968/1969 edition; price DM 4850)

Approx. DM. 4950  in 1963  and DM. 4850 in 1968 (Source: Büromaschinen Lexikon)

Repair information & pictures of internals