Mechanical Calculators

Home > Mechanical Calculators

Plus Adder

PLUS 506/D/815.357

PLUS Model 506/D/815.357.

Made in England by Bell Punch Co. Ltd. and distributed by Sumlock Compometer Ltd.

Key-driven ("Comptometer") type.

310 mm wide, 375 mm deep, 150 mm high (12.5" x 15" x 6"), 11.5 Kg (25.5 lbs).

185 mm x 180 mm x 127 mm. (7.25" x  7" x 5").


One of the more minimalist calculators made. Has 6 decades of keys, with only 1 to 5. To enter a number between 6 and 9 two keys have to be pressed in that column.

The knob on the right is for clearing the total.


Capable really only of adding lists of numbers to 9,999,999, but capable of doing this quickly and accurately (and cheaply !).

Click here to go to Sterling currency "Comptometers".

1) Mechanical Calculators
2) Desk Electronic Calculators
3) Hand-held Calculators
4) Non-Decimal Calculators
5) The Pocket Calculator Race
6) Calculator Companies
7) Calculator Photo Library
8) Calculator Articles
9) British Calculator Companies
10) Puzzle Corner
11) Calculator Time-line
12) Calculator Technology
13) Index to the Calculators
14) Calculator Resources
15) Frequently Asked Questions
16) Update Information
17) Vintage Calculator News
18) Bletchley Park
19) About this site
20) Search this Site

Mechanical Calculators

Golden Gem
S & N
Monroe LN-160X
Brunsviga 10
Curta I
Facit C1-13 & ESA-01
Plus Adder
Madas 20BZS
Burroughs Add-lister
Bowler Countess
Olivetti Electrosumma
Muldivo Mentor
SCM 1011 CB
Sumlock Comptometer 993s
Kingson Four-Rule
Imperial Office Master
Addiator Addfeet Junior

Vintage Calculators

© Text & photographs copyright Nigel Tout   2000-2015 except where noted otherwise.