Friden SBT10


The Friden SBT10 is a very  luxury full function high-end mechanical calculator. It has functions which are available on very few machines like a result register that can be split in two parts and a counter register which can be used to totalise results of a series of multiplications.

Because of its versatility it’s not an easy machine top 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 upper register.

Function of some special keys, switches etc:

Calculator Info
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Serial number:

Build 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 1967)

Ca. DM. 4950  in 1963  (Source: Büromaschinen Lexikon)

Repair information & pictures of internals