Rules for Record Attempts for Mental Calculation


Record attempts have to take place at a public venue (for example a university, a school or a science museum). Two witnesses must confirm the record, at least one of them should have a professional background in mathematics/calculating.
Record documentation should be sent to the "Book of Alternative Records".

Presentation of the Problem

The calculation can be done with the problem in view. The calculator can dictate the answer. He or she can also write it down in any order (from left to right, from right to left or even in any other order) or type it on a computer keyboard. It is not allowed to write down any intermediate results.

Number of Attempts

It is important to restrict the number of attempts for a record. The reason is that it should be forbidden to make a lot of attempts with newly generated random numbers and to wait for good luck with an easy task. For this reason the number of record attempts is restricted to 10 within a period of 24 hours. The calculator should clearly say when he or she stops practising before an attempt and starts with official record attempts.

Note: This rule also applies for all memory attempts, especially for the ones with a very short time for memorising like "most digits in 4 seconds" etc.


The timing begins when the task becomes visible to the competitor and ends at the end of writing/dictating the answer. Two stop watches should be used. At the end of the attempt the time should be taken as an average of the two watches.
Alternatively, the use of a computer program that shows the tasks on the screen, lets the calculator type in the answer, compares the result with the correct one and measures the time from showing the tasks on the screen until getting the last keystroke from the answer is also permitted. In this case, no additional stop watches are required, but of course the attempt must still be witnessed by at least two persons.
Correcting the answer while typing is allowed, however once the computer states that a result is wrong, no more corrections are allowed.

Computer Programs for Generating Random Numbers

The numbers used for the calculation should be randomly selected by computer immediately prior to the calculation and should be displayed to the calculator on a computer screen, board, screen or similar. It must be impossible to predict the generated numbers or their attributes

The  computer program for selecting numbers should be provided by the organiser of the contest, not by the calculator. If the computer program is used for presenting the numbers on the screen and maybe also for getting the result, the calculator should get the program for practising some weeks before the attempt.

The program must run on a computer provided by the organiser of the contest, not on the calculator's own computer.

In some cases, the calculator may use his or her own program. In this case, the procedure is as follows:

  1. The record breaker sends the source code and information on how to build / start the program to the referee from the "Book of Alternative Records" (soon enough before the attempt).
  2. The source code is checked and a working version of the program is built by the referee. (We reserve the right to refuse this task if the code is unreadable or if it would be necessary to buy licences for build tools etc.)
  3. The referee sends the executable program to the organizer of the attempt.
  4. The organizer installs the program on its own computer.

Attempts where the record breaker used his or her own computer or where the organizer got the executable program directly from record breaker are invalid!

It is NOT allowed to select the task by asking the audience for "random" numbers. Other methods for selecting numbers (like using mechanical devices such as a "wheel of fortune" etc.) may be allowed as long as every possible task has the same chance.

Approved progams that can be used can be found here:
MEMORIAD software (categories: Calendar 1600-2100, Multiplication of 8-digit numbers, Addition, Square Roots),
Javascript program for Calendar - Century,
K-Train for Calendar Calculation,
Division of a 10-Digit Number by a 5-Digit Number

Record List for Memory and Mental Calculation