Jaap's Mechanical Calculators Page


The Resulta E7

The Resulta E7
Promotional material
Articles and Advertisements

The Resulta E7

The Resulta E7 is a small rotary calculator. It has a 7-digit input register, a 7-digit output register, a lever to switch between addition and subtraction, and a clearing lever.

The Resulta E7, front
The Resulta E7, front
The Resulta E7, rear
The Resulta E7, input register
The Resulta E7, output register
The Resulta E7, input lever
The Resulta E7, input lever

There are 7 vertical slots on the front that reveal what looks like the side of a notched wheel. Next to the slot are the digits 1 to 9. You can insert a stylus next to the digit you want to enter, and pull it all the way down to the bottom of the slot. The wheel then stays in this position. This action sets a digit in the input register at the bottom, and also immediately adds (or subtracts) that amount from the main register at the top. Once you have entered all the digits of the number you are adding (or subtracting), the input register can be cleared and the input wheels reset for the next number by pressing down on the bar below the input register.

There is a small lever on the right front of the machine. If it is pushed down, it will keep the input clearing bar pressed down. This is useful when doing simple multiplications. It allows you to enter each digit several times in quick succession, but of course you can then no longer use the input register for verifying your input was done correctly.

The lever at the top right can be pulled forward and down to reset the main register. Note that the clearing lever can only be used when in adding mode. In subtracting mode it will not move.

To subtract numbers, move the lever on the left to the upward position (push it to the right to free its catch and then move it upwards till the catch re-engages). The number wheels in the register will move upwards, disengaging from the input wheels. Instead, an intermediary set of wheels is engaged with the input. This intermediary set of wheels causes the number wheels to be turned in the opposite direction by the input wheels.
Simply enter the number you wish to subtract. The input register will display that number as before, but it is now immediately subtracted from the main register instead of added.
The clearing lever is blocked from moving while in subtraction mode, so to clear the register you have to switch back to addition mode first.

The Resulta E7, output register addition
The Resulta E7, output register subtraction
The Resulta E7, bottom
The Resulta E7, date

There is no serial number, but there is an inspection date scratched on the bottom, in the form MMYY or MYY. In my case it is 763, so it was made in July 1963.

The casing is spot welded together, and riveted to the base. Only the face plate can be removed, giving a limited view of the inside mechanism.

The Resulta E7, inside, before input
The Resulta E7, inside, after input
The Resulta E7, input wheels
The Resulta E7, output register addition
The Resulta E7, output register subtraction


The Resulta was made in the Maschinen- und Werkzeugfabrik Paul Brüning (Machine and Tool factory Paul Brüning) in Berlin from 1927 to 1943 and 1950 to 1969. The first few years it was named the Minerva, only did addition, and had no input register. Clearing the register was done by turning a crank on the right hand side of the machine. It came in two sizes; a 7-digit and a 9-digit register. In about 1930 it was renamed to Resulta, and for a few years after that four main variants were made (with or without input register, with or without subtraction). These were called Resulta A, B, AS, and BS (B = with input register, S = with subtraction). By about 1938 only the BS7 and BS9 models were being made. Presumably the other models were not cheap enough compared to the BS version that it was worth foregoing the extra functionality that the BS offered.

In 1943, the workshop in Berlin received bomb damage, and had to be closed. It took until 1950 before production could be slowly started again, though some other manufacturers had been making licensed copies of the design in the mean time. In 1955, a version was created called the Resulta P7 or P9 that could print the numbers. The normal Resulta BS had seen only minor tweaks in its design since the 1930s, such as improved sound proofing, but in about 1960 the clearing crank was replaced by a clearing lever. The "Export" model, the E7, was simply a repackaged version of the BS7 made for the international market.


Promotional material

Resulta AS flyer
2-sided sheet
159mm × 238mm

Articles and Advertisements

The only reference to Paul Brüning I found in online newspaper archives is the notice of the founding of his company.

1921-04-30 Berliner Boersenzeitung

Here are some of the adverts for various Resulta models from online newspaper archives.

1930-06-11 Neue Zuercher Zeitung
1934-09-14 Het nieuws van den dag voor Nederlandsch-Indie
1934-09-22 De banier
1934-09-26 Het nieuws van den dag voor Nederlandsch-Indie
1934-10-10 Het nieuws van den dag voor Nederlandsch-Indie
1934-12-11 Het nieuws van den dag voor Nederlandsch-Indie
1934-12-13 Bataviaasch nieuwsblad
1935-01-19 Het nieuws van den dag voor Nederlandsch-Indie
1936-01-17 Bataviaasch nieuwsblad
1936-01-25 Bataviaasch nieuwsblad
1953-12-18 De Telegraaf
1954-04-03 Limburgsch Dagblad
1956-02 The Office


PatentFiling datePublish dateNameDescription
DE 538,6973-6-193020-11-1931Paul Brüning Maschinen- und WerkzeugfabrikCarry mechanism
See also CH 158,869.
DE 640,41727-8-19324-1-1937Paul BrüningRestraining device to prevent overruns
See also DE 1,693,164 U.
DE 1,645,297 U19-4-195216-10-1952Paul Brüning Maschinen- und WerkzeugfabrikSound damping strip
CH 309,2266-12-195231-08-1955Paul Brüning Maschinen- und WerkzeugfabrikCarry mechanism
CH 339,40921-9-195530-06-1959Paul BrüningSound proofing
DE 1,106,52722-10-195510-05-1961Paul Brüning, Johannes ThiemannDisplay shutter
See also CH 343,155
DE 1,103,65429-10-195630-03-1961Paul BrüningClearance lever
DE 1,116,92629-11-195609-11-1961Paul BrüningResulta P7/P9
See also DE 1,832,227 U, CH 356,940, FR 1,185,254.
DE 1,759,035 U28-4-195719-10-1957Paul Brüning Maschinen- und WerkzeugfabrikReversing mechanism for ink ribbon


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