



Addipresto 
Model 


Maker 

Brevetti Lanza 
Origin 

Italy 
Date 

1950s 
Serial 




A neat desktop adding machine.
A stylus is used to pull down on the bands. The
band is pulled right to the bottom causing the total
in the window above to change. Only adding is possible. 

The red lever on the left clears
the display to zero. The stylus would have been
placed in the hole on top when not in use. Mine
is missing and marks on the number bands suggest
a pen was used. This would have been better for
the operator who would need to write down the results. 

Care must be taken as it is
possible to pull the bands too far and cause a 9
to be added as 10. 



Addipresto 
Model 


Maker 

Brevetti LanzaSavona 
Origin 

Italy 
Date 

1960s 
Serial 




This is a decimal version and
is complete with box, cover, stylus and instructions.
Subtraction is possible using a number's complement.
The advert and the instructions show this model
was ready for use with decimal money introduced
in 1971. 



The complement of a number (on this
machine) is the difference between that
number and 9. Using this system, the
complement is added to the value in
each column, including any column with
a zero. However, to finish the calculation,
a 1 has to be added to the result. 

This could have been avoided if the
righthand column had been marked with
complements of 10 instead of 9, with
zero treated as 10. 

The complements would have looked
like this: 

0 9 

0 9 

0 9 

0 9 

0 9 

0 9 

1 9 
1 8 

1 8 

1 8 

1 8 

1 8 

1 8 

2 8 
2 7 

2 7 

2 7 

2 7 

2 7 

2 7 

3 7 
3 6 

3 6 

3 6 

3 6 

3 6 

3 6 

4 6 
4 5 

4 5 

4 5 

4 5 

4 5 

4 5 

5 5 
5 4 

5 4 

5 4 

5 4 

5 4 

5 4 

6 4 
6 3 

6 3 

6 3 

6 3 

6 3 

6 3 

7 3 
7 2 

7 2 

7 2 

7 2 

7 2 

7 2 

8 2 
8 1 

8 1 

8 1 

8 1 

8 1 

8 1 

9 1 
9 

9 

9 

9 

9 

9 

0 


Using the revised table above, to
deduct 345 from 975 we would add the
red figures 9999345
where the carry will result in the answer
0000630. 

Another way of looking at complements
is to see the complement of any number,
of any number of digits, as the difference
between the number and 10 to the power
of the number of digits. 

The complement of 4 is therefore 10
 4 or 6, the complement of 44 is 100
 44 or 56, the complement of 1234 is
10000  1234 or 8766. You will see that
these match the revised table. 

The complement of 0000345 (padded
with zeroes because we have a seven
column adding machine) is 1000  345
or 0000655, the values in black alongside
the red 9999345
used above. 







