Olivetti 
Model 

Summa 15 
Maker 

Olivetti 
Origin 

Italy 
Date 

1950s 
Serial 




A version equipped with additional 10 and
11 keys for sterling £sd currency, but
no halfpenny key. 

A joystick selects subtraction, subtotal,
total or number not to be included. The amount
is entered, the joystick set if required and
the handle pulled forward and released. The
amount is printed on a paper roll, in black
for individual amounts and in red for the
total or subtotal, using a typewriter ribbon. 

Pressing either the 10 or 11 key locks the
keyboard to ensure that these values are registered
only as pence. 

Care must be taken to enter a zero in front
of single digit shillings amounts after pounds
have been entered by pressing the large black
key (twice if no shillings). Any amount of
shillings higher than 19 will be reduced to
below 20, for instance 33 will register as
13. 

The striped knob at the bottom right moves
one notch to the left for each digit entered.
Pulling this to the far right clears all numbers
entered. 

There is a sliding control above this which
allows multiplication. This is achieved by
entering an amount, setting the control to
multiplication and pulling the handle the
required number of times. There is a counter
on the left of the keyboard so that the operator
can see how many times the amount has been
multiplied. 

There is a slider to the left of the joystick
to disable the entry of shillings and pence,
calculations then being in whole numbers. 

At the top right is a rotating manual paper
feed control. 

The original design dates from 1949 but
the machine was probably made around 1960. 

This machine is quite heavy. 